LittleBigPlanet PS3 & PSP: What's the difference?

I noticed this handy little game in the PSP section in my local Xtravison, I have the PS3 version with NO downloaded content.
Is it worth "buying" LBP PSP from www.pspisoz.com?

Since it's just a download away, why not play it?The PSP version is LBP with just two depth of field's (I really don't know what to call them) as opposed to 3 on the PS3. It also has a new single player, which is what you'll be playing a lot considering you can't play any levels online (I don't think). Other than that and the graphics downgrade, not much of a difference.

Both the psp and ps3 have downloadable content such as levels, skins etc...I think it's just a portable version, and before you ask...no idea if this can connect with the ps3 one.

psp one has different levels, and slightly different gameplay. Also, no multiplayer.