Whats difference between default skin and custom skins on Sims 2?

Davis Zou: default = based from the games creator just a regular skinscustom = man-made skins it'll more good than default skins because it's unique and well yeah the appearance much better than default skins

Gaylord Barragan: default = based from the games creator just a regular skinscustom = man-made skins it'll more good than default skins because it's unique and well yeah the appearance much better than default skins