ExcelForum.com vs StackOverflow.com

I was at dinner last night with two past programmers at Microsoft. I said I answer questions at ExcelForum.com. They asked what was the difference between it and StackOverflow.com.

I told them that there were a lot more questions being posted on ExcelForum (not knowing if it was true or not) and we allow files to be attached while StackOverflow does not.

They asked if we have the "Like" (thumbs up) feature so the best answers would filter to the top, and I said no.

Do you have any major differences between us and them? I'd like to give a better answer next time.