Mauresmo has 1 less slam than Capriati but she won the WTA Championships which is atleast as big (most on this forum atleast when it comes to the ATP say much bigger) than the Olympic Gold, and her combined WTA Championships/Olympic achievements of 1 WTA Championship title, 2 other WTA Championship finals + Olympic silver far trump Capriati's 1 Olympic Gold and no WTA Championship finals. Mauresmo has 25 titles to Capriati's 14, 6 tier 1 vs only 2 for Capriati, and 21 Premier titles vs only 6 for Capriati, spent more time ranked #1, was ranked #1 in the middle part of 2 different years unlike Capriati, etc....so this is one of those cases where the monstrous difference in their other stats are enough to overcome just 1 extra major. Especialy when Mauresmo won Wimbledon which is more prestigious anyway, and Capriati never even made a Wimbledon or U.S Open final.
So yes Mauresmo did overall have a better career than Capriati despite winning 1 fewer slam. Because of that most people rate her as a better player though, and I think Capriati is the better player of the two despite having the lesser career. Capriati's historic great U.S Open semifinal matches even in defeat, and her record vs Serena, and her precociousness make her a better player than Mauresmo despite Mauresmo's greater career, but it seems most dont feel that way which is overrating Mauresmo IMHO. Likewise Mauresmo also had a better career than Pierce, and because of that most assume she was the better player, but I think Pierce is also a better player than Mauresmo despite her lesser career.