An opinion, whether it is grounded in fact or completely unsupportable, is an idea that an individual or group holds to be true. An opinion does not necessarily have to be supportable or based on anything but one's own personal feelings, or what one has been taught. An answer is a reply, or a solution to a problem. It can also be just a short response like a yes or a no.

Your answer is a proven statement and your opinion is something "You" personally think or feel so It may not necessarily be right.

An opinion is usually based on personal feelings about a topic. An answer is many times based in objective facts. However, there are opinionated answers, in this case you can say to someone 'that's your opinion and i disagree'.