Hey Ger,
heres a list from the old uk mailing list archives
3.Thinner windscreen, I had to buy a new seal when replacing mine.
4.Limited to 180 kph /112mph .. (before you remove the screw in the cluster

)
5.No rear fog light
6.Sealed beam headlights
7.Red reflectors
8.Rear numberplate surround is square

9.Catalytic converter overheat warning light in dash
10.Hole in Cat for overheat warning sensor

11.Roadsters not fitted with a hard top were not supplied with 'Frankenstein'
bolts.
12.The side hard top mounts were not fitted to Roadsters unless a
hard top was fitted in production.
13.Fuel filler restrictor not fitted to Roadsters. Not that you'll find leaded petrol anywhere too often

14.Instrument panel warning lights on Roadsters include one for seat belt not fastened - and there's a buzzer for seat belt not fastened.
15.MX5's have a hazard flasher warning light and a 'rear fog light on' warning on the instrument panel
16.Double DIN radio was fitted to Roadsters
17.Automatic gearbox is available on Roadsters. There are a lot of specification differences with automatics - radiator, camshafts, etc are different, apart from the gearbox.
18.In 1994, a bigger (1.8 litre) engine was fitted. UK versions of this have EGR (Exhaust Gas Recirculation) fitted. Roadster versions do not.