Well duh roblox is a suckish game. It takes like two weeks to get SOME skills at it, it's full of little kid jerks, your places are bound to suck if you can't code in LUA, and it's all around full of glitches. Where as Blockland has (as I'm guessing) been perfected and developed for larger amounts of time and uses a 20 dollar fee to keep idiots away.
Summary: Roblox BETA = Suck, Roblox Complete = Maybe Not?, Blockland Current = Pwning