Hello thanks for choosing Dell. I'm not too familiar with the terms- would you be able to give me the reference you came across and show it to me so that I can find out further?
Respectfully,

How can I tell if a Dell drive Compellent is an enterprise plus or enterprise value version? - the only way that i know for sure is by plugging the drive in and using the CLI to get information off of the drive. command would be

#>drive get *driveIndexNumber

example #> drive get 17

and then you would look at 120 driveline and that will tell you if the system sees it as enterprise plus or enterprise value. 

is there a way to differentiate between a Dell Compellent drive and an EqualLogic drive with the same part numbers? - this one is more complicated as i have had drives with same PN and model and one will work and one would not work. Also to make it even more confusing some SSD's i know work in both compellent and equal logic. unfortunately there is no posted table that will tell you if it works or not in your compellent machine. To some degree i could tell you if it would work or not but its impossible really to tell looking at the HDD label. You cant look at the label because i have seen it where the firmware does not match what the label says. 

hope that helps some.