Specifically, almost all blocks have the same characteristics when it comes to construction. Wool and Iron have the same tensile strength. The only thing relating to structural integrity that varies from block to block is explosion resistance. For instance, a TNT block detonated next to a stone wall would destroy one layer (one meter) of the wall, but the same TNT block detonated in the same place would take out two layers of wood or three layers of dirt or wool.
Minecraft physics are crazy in many ways. Most blocks aren't subject to gravity. If you stuck a block onto the side of a pillar of blocks, it would just hang there. Even if you removed the pillar the block would still stay there, floating in air. The only blocks which are subject to gravity are gravel and sand: if there is nothing beneath them, they will fall. And of course, players, mobs and items are also subject to gravity.
Water is totally wonky as well. There are two kinds of water blocks: source and flow. Source blocks can be collected with a bucket, flow blocks cannot. Flow blocks emanate from source blocks as long as there is no obstruction for up to seven blocks. Flow blocks favor southwest, but they're not *that* picky, but because of the way the algorithm works, strange things can happen in blocks which are southwest of other flow blocks.
It's... weird. To say the least.
Sadly, being a technology pundit is truly never having to say you’re sorry. You can be wrong for years and never lose your job.—The Macalope