For good - forever, permanently. Forever - forever, eternally More explanation.. "For Good" is often used when referring to something that has been happening so far, or until some point in the past, and from that time cease to happen. ( I returned back for good this time) On the other hand, "Forever" is often used with something that will continue to happen from the moment forward until the end of time so it is widely used with the auxiliary verb "will". ( I will stay forever with you ) Hope that helped! :)

As far as I understand, "for good" is used when we want to search a better place and we leave our present place and never come back in that context, they mean the exact same thing. :-) example: He's gone for good. He's gone forever. Oh, by the way, forever is one word and you had it written as two.

Sasha, The adverbial expression “for good” has a two-part meaning because it is a shortening of the original expression “for good and all”: Duval is gone for good and all. –1603 - The “for good” part means that the action is brought to a valid (good) conclusion; the “and all” part means “forever”. The idea is that you have done something in a way so that it will not need to be done again. You are doing it for the final time. “Once and for all” is a similar expression meaning “one time and forever.” “Forever” and “for good” can be synonyms but not in every case. This is because the adverb phrase “for good” gives a perfective aspect to the verb. For instance in the following sentences: -I will be leaving New York forever. This sentence can have two meanings according to the context: 1) I will be leaving New York and not coming back. 2) I will never stop trying to leave New York, but I will never succeed. -I will be leaving New York for good. This sentence has only the meaning: I will at some time in the future be leaving New York for the final time.