What is the difference between a computer case and tower?

Is their a difference. Like online, i want to buy one and it says, ';computer case';. Is it only 'external'?What is the difference between a computer case and tower?
They are all computer cases...a tower stands up though and sometimes when they say computer case they mean it to lay horizontally on the desk.What is the difference between a computer case and tower?
A case is the metal box which holds the computer's components. A tower is just a vertical PC. Most desktop PCs these days use tower cases. The old cases were called desktop cases and they sat horizontal, and most people would sit their monitors on top of them. And this gets confusing since any PC that isn't a laptop may be called a desktop these days.





The difference in the name was about how they were traditionally used. The PC in a desktop case sat on the desk, and the monitor was usually placed on top of it. The PCs in the tower cases very often were placed on the floor. And it was called a tower because it stood upright rather than lay flat.
A case refers to any computer case, but a tower stands up, usually has bays for expansion of HD's and CD/DVD drives. blah blah blah