There is no functional difference between any given MX-5 and its alternately-badged Miata/Roadster/Eunos Roadster copies.
Other than that, what do you want to know? Some variants are heavier, some are more powerful, some have 1.6 engines, some have 1.8 engines, some have pop-up headlights and only two - both NA 1.6 Eunos Roadsters - are Premium.
They're as grippy as one another. You probably won't get much north of 300hp in any of them - my car of choice is the Premium NA '89 running 275hp with a supercharger.
If you click on my car list thread stuck to the top of this forum, you can see stock details on them all.