PIC's are the microcontrollers produced by Microchip. Currently a popular hobbyists PIC is the PIC16F628, with 18 pins. You can program them in assembly, or a higher level language if you have a proper compiler for your particular chip.
Basic refers to the basic stamp, which is like a PIC but programmed in BASIC, easier for beginners to use, and much more expensive.
pics are microcontrollers and microcontrollers are not microchips like pentium ones but cheaper and useful for some automation usage and other things.for example microchip's microcontrollers are called "pic" series and there are other microcontrollers like Motorola's...
so they have ram and pins to have the data analysed.hope this helps.if u like to have other information just look for the tutorials about pic. www.microchip.com
PICs are microcontrollers or uC's to be a uC and not just a MicroProccessor, u need to have your own program memory andor data memory, i say andor because some use sucky i386 like von barstard noimen architcture, which is blight on anyone that has ever had to upgrade their computers memory i mean jesus, u seen how much registered ECC memory costs in the UK <rants on>