I think Joey Maxim was a bit taller. Sugar Ray's defense was crisp. Maxim had trouble finding him. Robinson was using his legs but not as much as some modern boxers do. He wasn't running the way we saw a DelaHoya do or Ray Leonard in a few of his fights.
Robinson was 5'11. In the 40s and 50s, that was tall for a middleweight and it was very unusual for a welterweight. Someone can correct me, I'm sure, but I don't remember many world class welterweights who were 6 ft+ before the 80s (Hearns, McCrory, Breland). So Robinson had that physical advantage over most of his opposition. Maxim was a light-heavy and was the one time Robinson stepped up past middleweight but he still had an equal reach even though he was a couple of inches shorter than Maxim.
Joey Maxim & Bobby Dykes are on film. Other people he fought that were taller than him Jose Basora, George Costner. Fighters around the same height as him (5'10 +) Charley Fusari, Bobo Olson, Kid Gavilan, Jackie Wilson, Paul Pender, Rocky Castellani, Bernard Docusen And a lot of guys he certainly wasn't towering over e.g Randy Turpin, Georgie Abrams etc