The closest thing that standardizes size and shape is what's known as a "Form Factor". Common form factors are AT, ATX, BTX and ITX. The most common is ATX.
These form factors specify motherboard sizes and general component placement. For example, you usually need an ATX compatible computer case if you wish to fit it with an ATX motherboard.
A desktop computer is a personal computer (PC) in a form intended for regular use at a single location
desktop publishing
system of computer that is personal
operating system is a complete operating system that works on a desktop computer, a notebook computer, or mobile computing device.
Files and settings Transfer Wizard
laptop,desktop,system
embedded operating system
Apple parallels desktop computer
tower
windows by Microsoft
true
They are both the same but different names. Here are other words which relate to a computer: Computer Computer system PC Desktop/Laptop