the HUGE difference is that the target scope base takes ruger proprietary scope rings and they're expensive! (about 40 bucks per ring!), and the picatinny rail takes weaver rings (10 bucks a pair!)
Bought a Ruger rail from Midway
(about 20$) and all is well!
Now I am going for see thru scope mounts and a good quality pistol scope. Looking to shoot 100yds off a bench with it, just for fun!