See http://www.freescale.com/files/32bit/doc/app_note/AN4287.pdf for BSP (Board Support Packages)
PSP is not defined there but I am guessing that it may mean Project Support Package(?)
Freescale mentions that in Glossary section of MQX User Guide (MQXOG.pdf)
Board support package. A group of files that are specific to a particular type of processor on a particular type of board. It includes drivers.
Processor Support Package. A group of file that are specific to a CPU type.