This article explains the difference of Yahoo! Answers with message board or chat room.

Yahoo! Answers is a place for people to ask and answer questions in order to share knowledge.

Unlike a chat room, Yahoo! Answers is not a place for people to ask each other how they're doing or "talk" when they're bored. See the help pages for more information about the "chatting" violation.

Unlike a message board, where a thread of messages can continue indefinitely without ever getting resolved, the questions in Yahoo! Answers are resolved when a best answer is picked. After questions are resolved, members who have reached Level 2 can rate the Best Answer and everyone in the community can continue to share their opinions.