FPC and PIC

FPC 

-- M/T/MX-Series Flexible PIC Controller that slides into a chassis slot

   The "carrier card" (or controller card in Cisco-speak) that allows you to slot interface cards

reference:

https://www.juniper.net/techpubs//en_US/release-independent/junos/topics/concept/m20-overview-nog.html

http://forums.juniper.net/t5/Junos/PIM-PIC-FPC-explanation/td-p/26118