They are pretty close to the same. I would even use the one to describe the other. If someone asked "what does final mean?" I would say, "the last" Although there are some situations where only one of them is OK. In general, "final" is more specific and more formal. The word "last" is used for many, many things, but the word "final" is only used to describe one thing - when this is the last of something, and you are *really* confident this will always be true. So "last" is a weaker word and "final" is a stronger one. There is no possibility of confusion if you use the word "final." If you are in a really casual conversation with friends (drinking, having fun), it would sound a little weird to use "final" as an adjective unless it is one of those rare exceptions where "last" can't be used. I can't think of one of those exceptions off the top of my head.