For whatever reason, for almost all Kirby titles, the one on the American cover is always smoldering with rage, while the Japanese Kirby has a pretty carefree, happy-go-lucky expression. I'm guessing they probably did this to make Kirby look more hardcore than just a regular pink puffball normally would, in hopes that it would appeal to the average American consumer.

I present to you Exhibit A, Kirby Squeak Squad:

Japan -- image.com.com/gamespot/images/bigboxshots/4/933044_75969_front.jpg
America -- image.com.com/gamespot/images/bigboxshots/4/933044_75607_front.jpg

Your honor, if I may now present Kirby Air Ride:

Japan happy Kirby -- image.com.com/gamespot/images/bigboxshots/7/589687_24371_front.jpg
U.S. I'm gonna tear your shit up Kirby -- image.com.com/gamespot/images/bigboxshots/7/589687_front.jpg

Kirby: Nightmare in Dream Land

Japan pretty happy to be in a nightmare Kirby -- image.com.com/gamespot/images/bigboxshots/3/561703_23208_front.jpg
U.S. who is your daddy and what does he do Kirby -- image.com.com/gamespot/images/bigboxshots/3/561703_45152_front.jpg

I rest my case.