The first comment answers this well. I'd just like to add some analogous terms for Korean which might help clarify the concepts. If something is possible, usually this this is sort of a 가능하다는 뜻이나 된다는 뜻이에요. Whereas available is more like is more of the 여유가 있다는 뜻이에요. 예를 들면 결혼식 초대 받을때: 시간이 있으면 *available*이에요. Available으니깐 가는 것이 가능해요. That is, because you are available, it is possible for you to go to the wedding. 시간이 있기 때문에 결혼식에 가는 것이 *possible*이에요. Hope this helps :)

Hello 지은, Available means that something or someone is accessible. Also, available means there is some kind of resource that can be used or that someone wants to use (time, money, space, etc...). Possible means that a specific happening or action can take place. Possible means there is a possibility. The idea of availability is connected more to nouns. The idea of possibility is connected more to verbs. Here are two examples of each word for you: Available - The room is available. I am available to start work after May 30th. Possible - Is it possible to pay for the room with a credit card? Would it be possible for you to start work before May 30th? I hope this helps you to understand the difference between these two ideas :-)