Hi, the standard R has a 594cc engine. Different design wheels, reverts back to round speedo as the L has a square-ish dash. Different front badge. More simple interior compared to the L model.
Apart from that, not alot else I can think of. Im sure others will chip in with other details which I've missed.
I have a R model with the 594 engine. Upgraded the carb from 24mm to 28mm and she flies. Mind you . I have a lot of upgrades on mine. Sync gearbox is a must in my opinion if you intend to do lots of miles!