The one you pictured is a 93B w/a strike place at the bottom of the buttplate.
This is a 93A2.
From Magpuls web site.
Main differences are really cosmetic. The B looks smoother and doesn't have the pic rail at the top of the rear and has reinforcement plates on both sides as opposed to only on the right sides. Also on B models the receiver extensions are always the same color as the stock body as opposed to only black with a green, black or coyote body.
The easiest way to tell a 93B from a 93, A or A2 is that there's no ribs on the B model as in this pic.
Thanks man, I really appreciate it. Thank you.
And thanks for pointing out all the details, it was very helpful.
These are either discontinued or soon to be
Thats the bad news.
The good news is they are being replaced with 2 new ones. (plus the PRS)
See the info and pix of one here