Difference between staking and taking half of someone's action

[jfunky]

Just looking for clarification. To my knowledge, a stake is another player supplying your BR and you paying back the initial stake + splitting profits with him according to an agreement.

Taking half of someone's action is where I'm confused, is it just splitting profit 50/50 and paying back the initial 50%?

Sorry, I know this must be a noob question, just gotta know my poker lingo, thanks