Both buddy and pal is one and the same thing. Buddy is an informal way to refer to a male friend. Pal in an informal term used for a male friend or it can also be used for talking to a man who has made you...

Buddy is an informal way to particular refer to a male friend or it can be anyone. A friend is someone you hang out with in a group, someone to talk to, and to laugh with.

Buddy is an informal way to mainly refer to a male friend. Dude is a slang term in American English for an individual.

The main difference between friend and best friend is the fact that, while we may consider a number of people as friends, we only have a handful of best friends, usually only 1 or 2.