Is there much difference between population on Spineshatter PVP vs Thunderstrike PVE for EU TBC?

I started 2 Alliance characters on the PVE Realm. I'm not totally against world PVP but I thought it would be nice to level in peace. My priest likes it, although my hunter is having second thoughts about it.

I hear theres less people on the PVE realm, will that be a problem for instances leveling up?