Opportunity" has the sense that there is some specific goal and there is not as much pure luck required for success. For example: I earned such high grades last semester that my school gave me the opportunity for a scholarship. "Chance" implies more pure luck or randomness in being successful:: Since he bought so many tickets this round, he has a better chance to win the lottery. Many times we use these interchangably.

Chance is a noun = a possibility /accidental occurrence e.g. there is a chance you can catch this train. We only met at the movies by chance. Opportunity is a noun = a good chance/opening offered by circumstances.e.g. Congratulations! You have been given the opportunity to travel overseas.