the big thing about them is-
the sar is a imported high capacity magazine. the wsar is a low capacity magazine that has been converted.so, the sar is able to naturally fire double stack magazines while century has to file down the magazine well and get it right for the wsar to do it.
as a result of this, the wsar can have mag wells that aren't perfect and dont fit every magazine(without a quick and reallllly easy modification with a dremel) and it wont have the dimples on the side of the reciever the sar, and most other aks, have.
other things to note, because of the time in which the sar came in, it had to be following the AWB. as such, most of them that i've seen dont have a threaded barrel. you'll have to thread it yourself or pay someone to do it. the wsar comes with threads and the muzzle break on it. but the people at century have messed up some of the threads by crossthreading the break on there. basically, one is a 'no-ban' and one is a 'ban compliant' weapon.
what are you looking at?