I was just wondering what the differences are I know most of the mini sprints run the 1000 or bigger motor and the micro is a 600 but what else is different? Chassis? Ect?

10" vs. 13" wheels

Offset vs. Upright chassis

Rack vs. Schroeder-type steering box

They're not all that similar for both being motorcycle powered, chain driven, open wheel race cars.

This is so spot on. One of my pet peeves is people thinking they are the same car. I don’t know the exact details of width and wheelbase but a micro is a smaller overall car too.

All accurate. Micros have the engine offset significantly to the left and the driver's legs fit down in the chassis, beside the engine, similar to what you'd see in a go kart. Minis have the engine mounted more centered and the driver sits upright (like in a midget or sprint). Both engines are mounted transversely with the crankshaft perpendicular to the frame rails where a midget or sprint has the crank oriented parallel.

In the 80's, we called them "Mini Modifieds", "Sidewinders", and later "Modified Midgets" (i.e. National Modified Midget Association, NMMA) typically with 250cc 2-strokes and some Rotax snow mobile engines. 1200cc were "Mini Sprints". In the 90's, 250cc Modified Midgets gave way to "600cc Mini Sprints". By the late 90's-2000's, 600cc powered cars were branded as "Micro Sprints". 1200cc Mini Sprints reduced engine size to 1000cc (still called Mini Sprints) and now, they are commonly called "Lightning Sprints".

Also on the Mini sprint/Upright Mini sprint/Lightning sprint cars. Primarily 1000cc in the USA. The chassis is very similar size and wheel base to a midget chassis. Some people including me convert midget chassis over to run a bike engine and chain drive. Personally I have converted and run a 1999 Stealth Midget into a lightning sprint. Another one that gets converted a lot is the Triple X Midget chassis, but I have seen people convert a Spike, Bullet, DRC and a Ripper.