Ok, so the basic difference is this: Opportunity is something definite; possibility is about something that may or may not occur.

Also: you cannot HAVE a possibility. You would say: THERE IS the possibility that ...or THERE MAY BE a possibility of +- verb in the -ing form;

Also possibility is not followed by an infinitive, where opportunity <em>can</em> be followed by an infinitive.

Thanks for participating

Kanwalmalik, a great try. I will answer when I have a couple more answers.

Opportunity is a set of different circumstances that makes a thing possible. Its a kind of having change or favourable possibilities. If a person have opportunity to avail to get one step closer to their aims and goals that’s a favourable moment or window of opportunity to choose to achieve their aims. While, on other side possibility means situation created either favourable or unfavourable towards life ambition. So, in short favourable possibilities makes better opportunity.