Not just UNIX command names are case sensitive, but they are cryptic too. For example, ls, mv, cp, rm, and more. Unix and Linux commands are usually no longer than two or three letters. There is a historical reason. Unix was originally developed systems that had teletypes instead of CRT terminal. Typing teletypes were painful and often accompanied by bzzzt-clunk sounds whenever one struck a key, and a fast operator could do about 15-20 words per minute. Hence, shorter names for commands.
Why UNIX has short command names
Here is another explain: