The difference is the engine.
Cars use a four stroke engine. The term four stroke comes from the number of times the cylinder goes up and down for the engine to burn the petrol and empty the engine of the smoke - Induction, Compression, Ignition and Exhaust.
This means however when you increase the speed of the engine, the engine has to work harder and has more difficulty effectively completing all these strokes. This is ok though as allot of engines do not have to run quickly and only cruise at 3000-5000 Revs. 4 stroke engines will give out if you go over 8000-10000 for a prolonged time, cause of damage to the head of the engine.
2 strokes- here the oil that lubricates the moving held at the bottom of the engine. Since there is no head ( the thing that controls the valves that open and close to let the petrol in and the smoke out)the engine is lighter and smaller and can rev higher.
Along the sleeve of the cylinder there are two flaps. One to let the fuel mixture from the bottom of the engine in and the other to let the smoke out.
The result being that you half the number of strokes.
Induction and compression become one stroke and Ignition and Exhaust become one stroke adding to 2 strokes.
2 stroke engines run much faster, but are smoky, nosier, and they make this, clang clang clang sound!!!. They are commonly used in high performance bikes(TT racing), and you can drive them at higher revs and a little harder. You can also put this synthetic 2 stroke oil in, that burns at a higher temperature. It leaves this sweet smell behind and will give you better acceleration, you can be popping wheelies at the green lights!!!
Also for 2 strokes, power is given every 1 revolution of the shaft(the spinning bar that comes out of the engine) while with 4 strokes, it is 2 revolutions of the shaft. Cars overcome this by having 4 or 6 cyclinders, meaning the power to the shaft is more constant.
I think they are in the process of banning 2 strokes as they pollute the place pretty badly with a blue dirty smoke.
Better to get a 4 stroke bike!!
There are not really any two stroke bikes. What you buy is a bike with either a 2 or a 4 stroke engine. The size of the engine can vary between 50 and 1100CC and performance can vary greatly within 2 strokes depending on what way they are tuned.
92 95 98 has to do with the type of petrol. One is unleaded and the others have different octanes. The higher the octane the more power