The difference between Curry and Lillard is that Curry shoots 43% from three and Dame is around 37%, which is a pretty big difference given the amount of volume those guys shoot. I'd argue that Dame is a more well-rounded basketball player due to being a superior athlete, but Curry's godly percentage combined with his unlimited shooting range is such a massive advantage in the pace-and-space era.
The 3fg% Is probably the most notable difference. Over his career Curry has also been:
• Much better finishing at the rim to 3 ft (.647 to .571 career)
• Better from 3-10 ft (.415 to .335)
• Better from 10-16 ft (.454 to .419)
• Better from 16-3 pt (.454 to .441)
• Better from the stripe (.906 to .889)
• Better at scoring (24.6 to 23.9 pts per 36)
• Better at rebounding (4.7 to 4.1 per 36)
• Better at assisting (6.9 to 6.4 per 36)
• Better at stealing (1.8 to 1.0 per 36)
• Better overall on defense (+0.4 to -0.7 DBPM)
He has also been significantly better and more efficient in the playoffs:
Curry (in 37.8 mpg) 26.5 pts on .609 ts / 5.4 reb / 6.3 ast / 1.6 stl
Lillard (in 40.5 mpg) 24.8 pts on .544 ts / 4.8 reb / 5.9 ast / 1.3 stl
Curry’s just a bit more elite at most of the things Lillard is elite at, and I’d argue the better-rounded basketball player when you look at rebounding and D.
In Lillard’s column... he does fewer boneheaded things — turns it over less and fouls less — and gets himself to the line better. Also, as noted, he’s been significantly more durable over his career, despite typically carrying a heavier minutes load, with fewer high-level teammates to take the pressure off him. Plus at age 30 he’s peaking as we speak, where Curry at 32 may have crested.
In any case, being ~90% peak Curry is nothing to sneeze at. I’d argue he’s entered the conversation for “best small player ever not named Curry” with CP3, Nash, Stockton, and maybe a couple others (you can add Isiah if you must; we don’t have to rehash that conversation, haha).