>>279651393
-small irises
-hair is predominantly outline, little to no layering, there's a lot of split locks of hair in Precure's and Endro with small spikey protrustions that go in the direction of their hair, but Spice has mostly just the outline of the hair with random curls going wherever
-clothing is generic and lacks detail, Precure and Endro have ruffles in their shirts and skirts that go in and out and billow and bloom, Spice is flat and undecorated and franly lacking in discernability. Endro's pink girl has ovaloid triangular metal pauldrons with gold highlights and a sheen, Spice pink girl has a semicircle brown shoulder of seemingly indistinct material from the rest of her clothing. There's very little detail in each of the characters clothes to look at. Precure's mermaids have multicolored and patterned fishtails whereas Spice has monocolored tails with one or two tiny scales drawn in for detail.
-posing isn't as dynamic. I'm not very proficient in understanding perspective or foreshortening or whatever but the Spice pictures look a bit flat to me. Leads to it feeling like it has a lack of three dimensionality.
+oddly enough, both Precure and Endro have a little white/foggy filter over them whereas Spice is unfiltered. I wonder if this shitty fog/whatever filter contributes to the anime feel?

I'm sure an actual artist could find better or more valid reasons than I could with my uninformed opinions