I'm not super familiar with the SD line (I only have a couple) but there's a chibi Gundam show called "BB Senshi" (in fact the longest running Gundam show since 87) where a handful of characters are iconic and this seems to be one of them.
I didn't know there was a size difference, but this is significantly larger than the Cross Silhouette SD kits, especially the head.
This guy has extra armor all around - The chest, front skirt, shoulders, foot armor, outer legs and helmet are all extra armor panels on top of a more modest looking SD.
There's an eye piece, a rocket cluster and an extra big and chrome colored V fin on his helmet.
He's stuffed with weapons, so you get:
2 grenades attached to his left shoulder
1 serrated Combat Knife
1 Rocket pod that attaches to his backpack
1 Cannon backpack
1 Bullpop submachinegun.
They all combine to become an arsenal on tiny cannon wheels.
The color separation is surprisingly good. There is a modest sticker sheet with a few color correcting stickers (black ones for recessed vents) and two foils for the internal and external crotch V fin.
You have a choice of 2 out of 4 pairs of eyes on a rotating block and finally there's a few green foil stickers and a neat looking coat of arms that you can put on the helmet. Sadly it's not cut for a rounded surface so it'll look a bit wonky.
It's a really good kit. I also *highly* recommend taking a look at the Zaku II SD kits, which have amazing quality.