speed and size. As numbers goes up, speed goes down, but so does cost, so you can have more. A CPU might have ~16k L1, ~2M L2, ~8M L3. Not many CPU's have L3 cache currently.
cache memory saves programs that you last used so that is takes less time when you click on a program to load it, cache memory is similar to when you save where you left off in a game.
ram is the...
In the most simplistic terms, hardware is tangible, software is not.
Things like monitors, keyboards, mice, printers, hard drives, etc. are all examples of hardware. They are actual physical devices...