They're basically the same. The N-Fabs have a wider, flat step area and a wide variety of finish options. The Go Rhinos just have a small step plate bolted on the round bar and I think are only available in black or chrome. I have seen the Go Rhinos for alot less than the N-Fabs.
The Go Rhinos are identical to NFABs minus the step pattern. I believe they bought the design from NFAB, or something of that nature that allows them to use their same mounting points and bars and cuts/welds. I think the prices are similar. I went with the NFABS because I thought the step looked nicer, also I got the texturized finish instead of just gloss black. I like them, look pretty sharp and tough. They mount to existing holes in about 20 min with 1 buddy helping and are very sturdy. Lose only 1 inch of clearance at best, which is great compared to most other nerf bar options. You cant go wrong with either.