What is the difference between GOOD and FINE?

If you're comparing "good" with "fine", I have to disagree with the above answer. It's not the difference between formal and informal English, but with the difference in meanings.

Good - positive, means good. 好

e.g. That's good. He's good.

Fine - less positive than good, meaning ok, acceptable, no problem, but not really good 可以接受， OK 啦， 無問題。

e.g. That's fine. He's fine.

下面個 discussion 講呢個問題講得好好。先說明，是針對 "That's good" "That's fine" 的分別，也有提及 I'm fine 的意思。有人覺得如果說 I'm fine 好多時會是相反意思，不是真的 FINE。

Lately I have noticed that people often answer questions with "That's fine"... I only use these words if I don't feel up to something. It seems to indicate that the person is doing one a favour. The worst is when you ask someone how they are and they answer with "fine". How do you interpret this or am I being over analytical?
IMO (sorry trillian :-) ) "That's fine" is an open-ended dig, it means "well, it doesn't really meet up to my high standards, but since I'm raking you over the coals and getting it at half price, it will have to do." Not abrasive enough to merit a retort, which is one way people begin to chip away at you and talk you down, with subtle digs. Less frequently, it means "well that will work, but it is not how I, in all my maginficence, would do it." :-)
"fine" by itself depends on how it's stated, but I've never found it to be good, unless you've cornered someone into not taking advantage of you and they don't have a better answer. Most of the time it means "fine, have it your way, you stupid rotten jack-a**." Others it's just "fine, I have no more patience for you."

When I say 'That's fine', I mean 'That's fine' - but I'm a little old fashioned that way. The only way to assess the 'irony' level in a post is to read the comment in context.
"If you follow Google's guidelines, that's fine" from an honest webbie, probably means they are encouraging you to follow the guidelines. From a spammer, it probably means 'don't make me laugh"
"If you don't mind being dropped from the index, keep using white text on a white page, that's just fine" is probably sarcasm.
Context is all!

It can depend on the tone but IMHO when a guy says, "that's fine" he generally means that's fine. When a woman says, "that's fine", she means the exact opposite ;)

I believe that it entirely depends upon the context.
As a reply to "how are you", it generally means "I know you don't really care, so here, I've fulfilled my end of the empty social formality, so let's get on with it".
In this case, the phrase is quite benign, and saves rather a lot of time and effort. If someone asks me if something is permissible, I may say "that's fine".
In this case, I mean "that's fine". If someone takes this as having some hidden meaning, that's fine, too.



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上面大意是說要看前文後理 CONTEXT。我的經驗，THAT’S FINE 是 不打緊，唔緊要，唔駛介意，無問題等等。而 THAT’S GOOD 便是好好。如果指人 SHE’S FINE 即是說她無事，當然不是好好的意思。

Besides being a noun, a verb and an adjective, FINE can also be an adverb whereas GOOD can only be an adjective.

I think:
good---formal or written english
fine---informal, oral english
e.g. How are you? I'm fine. But we seldom say: I'm good.