I think that the biggest difference is physicality. And probably playing level. I have to put my body under tons of stress that requires the use of proper equipment, you might be able to get away with LESS protection on clay against whoever you play but on hard court against the guys I play I need the cushioning and grip.
"IF YA AIN'T REPPING 180 ON THE BAR BENCHING, YA WEAK!!! ARGHHHH ARGH ARGH!!!"
-Scrub frat boy