I believe Answer will appear in your Contributions feed, Comment won't.
This isn't only about the counting :-) It also means you can't use Contributions to hunt down a thread you commented on.
Also, Answer will bump the thread to the top of the "Recent G2G Q&A" page, which is where many people come in. Comment will only bump the thread in My Feed and Recent Activity, so people are more likely to be unaware of it.
Also, Answers can be voted on and starred, and I expect they get more G2G points.