Right now they are more or less the same, the TRV gets +45 RPM in exchange for the "good" Hipfire accuracy of the TRV. And that's it. Will we see any adjustments to the TRV or the TAR?
TRV: 0.5x ads speed multiplier, longer reload, +45 rpm over TAR, more user-friendly recoil, pulls to the left, terrible hipfire. TAR: 0.75x ads speed multiplier, better hipfire, shaky recoil, pulls to the right. I'd say they are quite different (at least for cqc ARs).
The TAR is getting a slightly quicker short reload on PTS at the moment. I forget if the TRV is getting anything. Very minor buffs, no nerfs, no major differentiation between them but their roles are actually more distinct than you'd think. TIP: Just use the Cycler. It's plenty fast, it has better damage dropoff, and it's way easier to handle!
^ ^ ^ Don't forget it's also free! Slap a grip on that and you get to enjoy the only gun that feels like a pre-nerf Carnage running with adv grip and comp. It's a great, great gun.