To explain what I mean, let me give a little introduction.
In the Babylonian Talmud, Tractate Sanhedrin, on page 60, we find a teaching [called a "braita"] which tells us how do we know one is liable if he serves idolatry not according to its usual way. It says: We learn it from "He who sacrifices to the gods will be destroyed ." [Exodus 22] (i.e. If sacrifice is the usual way, then why mention it? It is already included in "How do they serve?" So it must be coming to tell us also not in its usual way is liable.)
Rava asks, why can't we learn instead from "least he will bow?"((Deuteronomy 17))
Rav Acha asks on Rava if we would learn from bowing then what would "How do the nations serve their gods"(Deuteronomy 22) come to tell us?
Why does Rav Acha not ask this same question on the original braita? That is the question both topshot and the Baal HaMeor ask.
Before I go further let me offer a little explanation. The point of the Gemara here is that we have two verses telling us the same thing. They intersect the same set.
The answer of the Meor HaGadol is yes they do intersect the same set but you might have thought they don't. You might have learning from "least he sacrifice" to make forbidden also things that are not the way of that idol, and yet still in the way of honor like kissing an idol that one usually hugs.
That is the verse "How do they serve" come in fact come to exclude something you might have thought even though in fact "sacrifice" does not forbid things of honor that are not the way of that idol.
Tosphot develops a different line of logic. He starts out showing that "How do they serve" comes to tell us at least things that are forbidden. His point is that even though the Gemara does finds something to it comes to permit still it is implicit that it forbids some things. So since the fact of the matter is that "He who sacrfices to the gods will be destroyed" (Exodus 22) and "How do they serve?" (Deuteronomy 22) in fact intersect the exact same set of permitted things, we have to understand the original question of the Gemara as being all inclusive what at all does "How do they serve?" come to tell us--that is even forbidden things. Because Tosphot is saying that we would learn everything from "bowing" even service according to its way-- even not in the way of honor.
But I might add a little background information for people that have only a little bit of experience with learning Gemara.
 Service to an idol is forbidden in two ways. One way is service that is usually done to that idol, like throwing stones at an idol that that is its way of worship. That is even though throwing stones at something is usually considered as disrespect, still if it is the way of that idol then one is liable.
Another way something can be forbidden is if it is one of four types of serve pouring wine, burning incense, sacrificing an animal or bowing.
 People can be objects of idolatry. This fact is not relevant to the above essay but still important to keep in mind.
But the Talmud itself does not go into much detail about what can be an object of idolatry. It was written in Babylon where the distinction between Jews going to their Temple and praying was clearly different from worshipers of idols going to their places of worship. Only much later did people like Saadia Geon and Maimonides have to deal with the issue of what can be an object of idolatry. But the fact that this is not talked about much in the Talmud means the issue remains blurry.
I want to show here a little of the depths of Tosphot. There is one line in Topshot that says something that seems to not fit the rest of what he is saying. I have already pointed this out that this kind of thing is found in almost every Tosphot in Shas. At first glance it seems like a mistake. Then after you think about it you start to see the point. And much later you realize that he was saying something essential to his argument. Before Tosphot states his answer he says "and without 'How do they serve?' we would not know service according to its way not in a way of honor would be forbidden." True, but it seems to be the opposite of what he is trying to say. What could his point be? And it can't be part of his answer which says just the opposite. I want here to say that Topshot is reinforcing his question-in this way: We know that, "How do they serve?" has no intersection with bowing or with sacrifice, so what could the question of Rav Acha be? Of course we need "How do they serve?" We would not forbid throwing stones at Markulis (an idol that one serves by throwing stones) without "How do they serve?" So we have to say there is some intersection with bowing that we would not have with sacrifice. Tosphot is trying to get to his point that bowing would forbid quadrant IV (Its way and not a way of honor). But here his point is that without saying that "bowing" forbids something in quadrant IV, we would not ask "What does 'how do they serve' permit?" We would not ask such a question unless it did not forbid something. So Tosphot is asking two questions. Why does Rav Acha not ask on "sacrifice" also? If you learn from "sacrifice" then what does "How do they serve" permit? So the Gemara has to mean that it has gone through the options of what "How do they serve?" might forbid and found nothing. How is that possible? It must be because "bowing" forbids everything that "how do they serve" forbids. And if "bowing" would not forbid something in quadrant IV then the question would not even start because we would need "How do they serve?" for that quadrant. A simpler way of putting this is this: Tosphot considers the question of the Gemara in two ways. He asks himself: "What does it mean to ask what do we need 'how do they serve?'? Does it mean, what does it forbid? But that can't be because we know it forbids something that neither "bowing" nor "sacrifice" forbid --i.e. all of quadrant IV. Then maybe it means, what does it permit? But that also can't be because then why ask it only on "bowing" and not on sacrifice also? (Because both "sacrifice" and "bowing" and "How do they serve?" all allow quadrant III.) Tosphot concludes that therefore we have to say that "bowing" and "How do they serve?" that both forbid quadrant IV and that is the reason the Gemara asks only on "bowing." The Meor Hagadol asks the same question but as I mentioned he answers it differently. He says we use "How to they serve?" (Deuteronomy 22) to tell us things in quadrant II are permitted that we might have thought are forbidden e.g. kissing an idol that one usually hugs. That is a good usage. But we can't do the same thing with "bowing" because "bowing" in fact forbids that very thing. Appendix 1) I wanted to add one small detail that I hope was clear. It is that if we learn from "bowing" then all quadrant II would be forbidden--i.e. service not like the normal way and yet in the way of honor. But in fact we do not learn from "bowing" anything except to tell us that it is a forbidden kind of worship towards any idol. The verse that we do learn from is "least he go and sacrifice" and that tells us all types of service that were done in the Temple are forbidden-not just any kind of honor.] 2) I also wanted to add a point that I skipped in the above essay because I thought it would detract from the continuity. It is the reason why Topshot is considering the question of the Gemara in two opposite ways. I.e. what does, "How do they serve come to exclude?" clearly the Gemara clearly tries to find what does, "How do they serve?" come to permit. So why does Topshot treat it as, "What does it come to forbid?" The reason is contained in the very cryptic phrases of Tosphot. He exclude the possibilities of coming to permit because what ever bowing permits sacrifice will permit more. So Tosphot is showing why he has to go to the opposite direction. 3)Tosphot thinks that there is no way that "sacrifice" can possibly be expanded to all of quadrant II (not the way of that idol but honorable service). And therefore there is no reason we would need how to they serve to eliminate it. That is the essential reason he disagrees with the Meor Hagadol. And in that he seems to have a good point. And Tosphot does not need a extra verse to tell us that all kinds of serve done with honor are forbidden because the gemara understands that that is the essential meaning of bowing.[Actually this last point I am a little fuzzy on. Why would Tosphot not need a verse to expand bowing to all the things he wants to expand it to?!!!] 4) One thing I did not mention is that according to way of thinking of the Meor HaGadol when there might have been a prohibition for all of quadrant IV and "how do they serve?" tells us that there is in fact no liability there then how to we know which direction is determinate? But why? Maybe we should go with the idea that that area is forbidden and use "how do they serve" for something else?!