Opportunity 和 Chance 的分別

呢個係一個好問題！好多人會覺得兩個字係互通嘅，但其實喺意義同用法上有最少有以下嘅不同：

1) 如 Yelleagle 所言，opportunity 的確比chance 官腔（formal），chance比較多用於日常口語之中。

2) "chance" 多解作「機會（率）／可能性／或然率」，意思與 "probability"相似。
例句 "I've got a chance to be rich!" 可用於當講者啱啱買完六合彩之後。

而 "opportunity" 多解作「渠道／（可行嘅）方法」。kakat所言嘅「良機」係其中一個比較常用嘅解釋 。
例句 "I have got an opportunity to be rich" 可用於當講者諗到一條發達大計嘅時候。

以上純屬個人愚見，未必能百份百講明二字嘅分別。I really look forward to having more insights from any one of you!

Opportunity is a noun meaning "機會;良機"[(+of/for)][+to-v]

Chance can be used in various way as follow:
a/noun :
1)偶然;運氣;僥倖;意外
2)可能性,希望[(+of)][+(that)]
3)機會,良機,際遇[(+of)][+to-v]
4)冒險;賭博[(+of)]

b/verb :
1)冒...的險;賭(錢)[+v-ing]
2) 碰巧;偶然被發現(或找到)[+to-v]

c/adj : 偶然的;碰巧的;意想不到的

You may find the examples thru' Yahoo Dictionary:
opportunity : http://hk.dictionary.yahoo.com/search.html?q=1&s=opportunity
chance: http://hk.dictionary.yahoo.com/search.html?q=1&s=chance

i think they are mostly the same... except chance can be used several ways... and opportunity can be used in more formal conversations (cuz it looks like a harder word... xd)