Blockland is based off of Lego.
Roblox is based off of a 3D block physics and interaction simulator called Dynablock; Roblox (Robot Blocks) was called Dynablox (Dynamic Blocks), but changed its name because of the similarity to the program.
Minecraft, and pretty much any voxel-based game, is based off of Infiniminer.
Blockland uses Bricks.
Roblox uses Blocks.
Minecraft uses Voxels (Volumetric Pixel)
Blockland is a social building game.
Roblox is a socialite game; socialite because of over protection on the freedoms of players.
Minecraft is a loner RPG survival game; multiplayer is just an extra feature.
I have played all three, and have been obsessed with each of them throughout my life; Roblox was like 9-11 y/o, Blockland is 12-current, Minecraft is 15-current. I tried playing Roblox again over the past summer, but the game; is filled with immature 6 y/os, has stuff FPS, glitches too much, terrible graphics, terrible playability in general. Minecraft is slowly getting better with each new update; that being that trying to play a non-1.4.5 version is boring. Blockland was pretty good, then got immediately better, faster, and clearer after the V21 release. I feel like minecraft and roblox just have terrible communities because they became instant hits. I don't want Blockland to end up like this, and I fear with a steam greenlight, this could happen.
OP, could you please remove the bias from your post, it is really discerning to see such scrutiny about the other games when in fact most of your counter arguaments are wrong, impartial, or completely warped.