Attempt to compare two userdata values?

So I have defined local buildings succesfully to children of a folder but the problem I'm having is that a for i = 1,#buildings do loop goes through every building of the folders building[i] and I'm trying to compare the CFrame of the building[i] and the CFrame of the player's HumanoidRootPart. The CFrame of the building[i] should be smaller than HumanoidRootPart.CFrame * CFrame.new(0,0,-10). So the Z part of the CFrame of the building[i] should be smaller.

But the thing what I'm trying to do is that it checks is the building[i] behind or in front of the player's HumanoidRootPart.

Help highly appreciated !!!