RealGM

I don't see the difference between them.

Also, when a player is bought out, like Dice or Starbury, the amount bought out for would stay against the team's cap right? (So Dice's 3m stays on Denver and Starbury's 18+m stays on NY)

You are correct. They are several different angles of essentially the exact same process (the release of a player who has a contract). In addition, you can add the word "retirement" to the same list, because when a player "retires" with a contract still left to be paid, it's typically another version of the same thing.

All of them involve the player being released.
All of them require the team to "waive" the player - ie, make his contract open for any other team to claim, if they want (and if they have the cap flexibility to do so).
When it's done, the player is then a free agent and able to sign with any other team, if he wishes.
If you hear buyout, it means that the team and the player - in advance of the release - reached a financial settlement for the balance of compensation the player is due on his contract.

Coon's CBA FAQ has several sections on it, especially ...
http://members.cox.net/lmcoon/salarycap.htm#Q54
http://members.cox.net/lmcoon/salarycap.htm#Q59
http://members.cox.net/lmcoon/salarycap.htm#Q60

Thanks a lot.