In looking at the two, close-up, the only difference I see is that the new number appears to provide more protection on the outside edge. Since they are marketed as "brush guards", either one will probably do. I have the old style and somehow still managed to break a light. Partly because I only used two bolts, initially, and the fact that I hit a large branch instead of just brush. I ended up drilling two more holes in each side of the rops to utilize all four available bolt holes in the guards and the light assemblies so there would be no twisting when a branch was encountered.
I'm currently working on a rops mounted LED setup with side-visible lights and "branch guards" so I never have to worry about breaking a light assembly again. My setup will move all lighting in line with the rops instead of inside the rops where they'd interfere with access to the backhoe.
If you don't have the backhoe, just move your lights to the inside of the rops and forget about the brush guards. If you decide to move them to the inside of the rops, you'll have to swap the left side assembly to the right side and vise-versa. It's not hard at all. You'll need a couple of replacement plastic wire-ties and a coat hanger to do that.