Diffrence Between HDD Model

Hello
If possible, please advise what the difference at the end of EMC hard drive models means.
for example :

EMC FLN42S6F-200TU

EMC FLN42S6F-200U

EMC FLN42S6F-200

FLV42S6F-200-FP

What is the difference between TU - U - FP ?

Thanks