Basically the same tyre, same compound and construction. The T1-R has an improved tread design along the edges to give the tyre better wear characteristics
Yes, my tyre history is SO2pp SO2 (horrible) T1-S T1-R
The front wheel T1-R outer edge wear is less than I experienced with the T1-S's. Not an absolute science because my use of the tyres varies between the S & R brands but it appears better.