I haven’t owned both but have sat in both. I didn’t measure, but back seat in S seemed to have more leg space. Mainly because I could push the seat back and recline - which I couldn’t do in the T. This means the third row folks would have less space, but I rarely use third row. Definitely more room for rear facing car seat in S because second row can slide back. I chose the S because I haul my kids more than objects and my kids prefer a roof over their head. Where I live, riding in the pickup bed is frowned upon.
The second row legroom is the same in both models.
However, there are two differences that make the R1S “feel” like it has more legroom:
1.) The seat pan in the R1S is shorter. So it seems like there is more legroom in the R1S because the distance from the edge of the seat in the middle row and the back of the front seat is slightly larger on the R1S than the R1T. But that greater distance is actually just because of the shorter seat pan.
2.) The middle row back rests in the R1S can recline and R1T’s second row back rests cannot.
That’s it. I have measured them both, and they are exactly the same. Yes, even with the middle row in the R1S slid all the way back.