I know that Raspbian is obviously a linux distribution, but could I run Raspbian on a mainstream 32 bit computer? Or could you run any linux distribution on the pi? Also, how would you describe the Pi system? For example for most windows computers its either 32 bit or 64 bit. Could you describe the pi in that way?
Raspberry Pi is a 32-Bit ARM style cpu. So, while in theory you should be able to get most 32-bit (not 64!) OS's to work on a pi, however, a lot of work will be needed to actually get them to run. Many popular linux distributions feature a pre-made image specifically for the pi.
Desktop PC's on the other hand are i386 or x86_64 which are 32 and 64 bit (non-ARM) respectively, and most computers today will be the latter, 64 bit. Because Raspbian is made for ARM, it will not work on i386 or x86_64 by default. However, A virtual machine can be used here. A bit of searching lead me to This question, which should lead you to get a VM of Raspbian running on your desktop pc.