What you may not be familiar with is that the many facets of this debate are moot points.
Mechanical Differences Between 2 Stroke and 4 Stroke EnginesThe biggest difference is the number of times the cylinder fires during a stroke. A "stroke" comprises of Intake, Compression, Combustion, Exhaust. A 2 stroke engine will do this by moving the piston up and down 1 time, a 4 stroke engine will take 2 times.
In other words a 2 stroke engine has a "power" cycle every time the piston moves up and down once, and a 4 stroke engine moves up and down twice to make power.
As you can imagine, you get more bang for the buck with a 2 stroke because you get more power with the same size cylinder.
Misconceptions About the Difference in 2 Stroke vs 4 Stroke EnginesThere are a few common myths people use when comparing 2 and 4 stroke engines.
The most common is that 2 strokes have to have pre-mix. (Mixing gas with oil). This is only a matter of simplicity. Take a look at Caterpillars; they have huge oil sumps, they have oil pressure AND they are 2 stroke engines.
Valves at the top of the cylinder head in 4 stroke vs reeds in cylinder walls on a 2 stroke is also false. Cruise ships have turbo diesel 2 strokes with poppet valves.
Emissions and MaintenancePeople will also try to tell you that 2 stroke engines produce more emissions than 4 strokes. In general this is true. But there have been huge advances in technology that has made 2 strokes able to run as clean as 4 strokes. Surrich/Orbital 2 stroke design on Mercury outboards is a good example.
Maintenance is more frequent on 2 strokes because they fire more and run hotter. You can expect to re-do the heads every few seasons. Fortunately, 2 strokes are much simpler and therefore easier to work on.
The Bottom Line: Power!
So, what's the difference? About the only difference between 2 stroke engines and 4 stroke engines, besides the number of times they fire in a cycle, is the amount of power they can make given that everything else is equal. Because the 2 stroke fires more often than a 4 stroke (twice as much as a 4 stroke), it naturally makes more power.