Does Anyone Know why some HP Servers have "R0xx" in the Product Name?

What I'm getting at, 90% of my servers have something like HP DL380 Gen7,8,9 or HP DL380 G7,8,9. That is standard names I'm used to. But a a few follow a name like HP DL380R07 or DL380R05 or something like that. The "R0" is throwing me off. And these product names dont have "Gen" or "G" in the name which is what I'm used to.

Any help would be greatly appreciated! I'm hoping this is the right place to ask...