Both are subject to long-term only afaik. And I'm talking about memes as in ideas that are copied without explicit instruction.

For instance, a specific image superimposed with text may be recycled and iterated on and eventually be forgotten, but the idea of meme generation itself--the act of coupling text and images to convey a whimsical truth--THAT is, in itself, the meme (reproduced behavior that is taken for granted).

Don't know if that clarifies anything--I'm no expert. Either way, I found it interesting.