2 strokes = 2 stroke to complete a cycle. ( intake, compression), (ignition, exhaust)
4 strokes = 4 stroke to complete a cycle., intake, compression, ignition, exhaust

A 2 stroke will also generate more RPM due to a longer rod and less strokes to complete a cycle.
The piston dose not have to travel as far as a 4 strokes.

A 4 stroke will generate more torque.

R/C intro engines have sleeving that are ported different by different manufacture.
The porting also effects performance.

The size of the carb also effects performace,of course.

obviously a .90 4stroke is lighter than a .72 4 stroke if it uses the same casing and the .90
has just been bored out. less material less wieght of course.

a .52 is lighter than a .40 of couse if it use the same size casing..bascially if you bore it out.lol

nitro heli 2 stroke engines also has a shorter rod than an airplane 2stroke engine.

Theres other factors such as prop pitch and size...air frame

You can have high RPM ,but if it's not moving air, it's just making noize.
mmm...kind of like getting on a multi speed bike and pedaling the heck out of it and hardly moving.

There's also a threashold or power band. Peak RPM dose not equal peak HP.

don't go crazy assuming you can use a car Nitro engine for air craft ..Car engine are in the 30000+range.
R/C props are not designed to spin that fast and will disintregrate.