PIC12F508 is a low-cost, high-performance, 8-bit, fully-static, Flash-based CMOS Microcontroller unit that has 8 pins out of which 6 pins can be used as I/O pins.
PIC16F72 is a low-cost, low-power, high-speed CMOS Flash technology capable, 8-bit, fully-static Microcontroller unit that has 28 pins out of which 22 pins can be used as I/O pins.
The PIC12C508 is low cost 8-Pin Microcontroller from Microchip. It is a simple 8-bit controller with four oscillators including 4MHz internal RC oscillators. The controller is very old and has been in the market for a long time now.
The PIC16F887 is an 8-bit microcontroller from Microchip. The 40-pin IC has 14 Channel 10-bit ADC making it suitable for applications which require more ADC inputs. The IC also has 2 Comparators, 2 Timers (8-bit and 16-bit) and supports SPI, I2C and UART communication protocols.