DDR3 PC3-10600, DDR3 PC3-12800

Memory Type: DDR3 PC3-10600, DDR3 PC3-12800, DDR3 (ECC)
Maximum Memory: 32GB
Slots: 4

Memory or DRAM is the "working" memory of the computer. It's used to store data for programs (sequences of instructions) on a temporary basis.

Installing DRAM/SSD in:
Mac Pro 4-Core Mid 2010
SATA

External Drive Bays -- 2 x 5.25"
Internal Drive Bays -- 4 x 3.5"
Storage Drives -- hard drives and solid state drives -- are the permanent memory for the programs and documents on your computer.
Data Transfer Rate is the rate at which data can be sent or received. This is determined by your motherboard. A drive with a higher transfer rate will only run at the rate of the motherboard's transfer rate.
Cache is a type of working memory that allows the drive to perform faster.
RPM is the rotations per minute of a hard drive which effects the speed of data transfer.
Solid State Drives are non-moving memory, so access speed is instant.