Are you scaling the meshes up in edit mode or in object mode? Manipulation in edit mode (scaling, rotation, moving) has no effect on size, rotation, or location attributes of an object - it manipulates mesh data.
If you scale planes in edit mode, any size mesh can display SizeX = 1.0, SizeY = 1.0, SizeZ = 1.0. If you scale two planes differently, their displayed size attributes will differ. In fact, the “size attributes” have nothing to do with the mesh data; location, rotation and scale parameters are properties of objects.
You can try this out by creating two meshes - a cube and a UV sphere. Then scale the cube up in object mode - that will change the scale parameters of the object to which the cube is linked. Now, go to the edit buttons and make a change in the MESH: block - click on the minus and select UVSphere. Now, the object you once knew as a cube is now a UV sphere, except scaled up a bit. If you go into edit mode and move around some vertices, you will notice that the vertices move on BOTH OBJECTS. You are using the same raw mesh data twice - and the mesh has two different sizes. That’s because size data is not specific to meshes; it’s specific to objects.
This explanation might be a bit lengthy and overblown, but I’d rather overdo it and try to explain clearly than assume you know a ton about the program and get nothing accomplished. I hope this helps -
Does this help?