Oh, this difference is actually very simple and straightforward.
Let us use as example that John's character somehow bothers Jane's character, with John claiming an RP motivation.
->This is RP if John's motivations for his action are to make the game more fun for both himself and Jane.
->This is griefing if John's motivations for his action are to make the game more fun for himself at the cost of Jane's fun.
In practice, motivations cannot be read directly from someone's actions. But a straightforward rule to establish motivation would be to ask: "If Jane asks John OOC to please leave her alone, would John comply?" If not, then he's griefing.
This is really the first rule of RP, that still many RPers in MMOs do not seem to get: "This is what my character would do" is never a justification that overrides OOC courtesy. It doesn't make you a good RPer, it makes you a griefer who only uses RP as justification. A good RPer would find a way to be true to their character in a way that is fun to everyone involved.
Let us use as example that John's character somehow bothers Jane's character, with John claiming an RP motivation.
->This is RP if John's motivations for his action are to make the game more fun for both himself and Jane.
->This is griefing if John's motivations for his action are to make the game more fun for himself at the cost of Jane's fun.
In practice, motivations cannot be read directly from someone's actions. But a straightforward rule to establish motivation would be to ask: "If Jane asks John OOC to please leave her alone, would John comply?" If not, then he's griefing.
This is really the first rule of RP, that still many RPers in MMOs do not seem to get: "This is what my character would do" is never a justification that overrides OOC courtesy. It doesn't make you a good RPer, it makes you a griefer who only uses RP as justification. A good RPer would find a way to be true to their character in a way that is fun to everyone involved.