the NSRmini is a pure track bike. No lights, bigger radiator, real adjustable suspension.
The NSR50 is a street legal bike. It has a generator and battery, lights, horn etc. The radiator is thinner though and the suspension is "suspension" only in the terms that it holds the bike up.
There is not even preload adjustment on the rear. Not even that cheesy notched ramp crap budget bikes call "adjustment"; the bottom spring seat is welded in place. The upper on the forks is not a true triple clamp, the handlebars bolt down through it into the top of the fork tube. The third gen actually has a true triple clamp and clip ons, mine is the second gen.
The nose dives at the slightest hint of front brake and then bounces back uncontrollably thereby allowing the rear shock or as I call it the "spring on a stick" to show just how bad it is. Low speed stops have a predictable see-saw action that can unnerve a person, high speed is lean far back and ease into the lever. I have gotten pretty good at riding with the deficiency but recently question why I have not fixed it. I am having the forks overhauled with thicker oil and shims on the springs to try to improve the nose behavior at least. I have large plans for the future and I don't want to spend a lot on a short term fix.
The engine is the same as the mini and pretty much bulletproof with good power for it's size and typical honda reliability. I beat it mercilessly and have only eaten one piston and that was completely my fault.
The brakes are also the same as the mini, two piston up front grabbing a 220mm crossdrilled disk and a one piston in the back. Neither are floating types but the system is very effective at scrubbing off speed and honestly just needs steel braided lines to be perfect.