Re: Four cylinders or 2
That's what I thought you meant. Two stroke engines have no valves. They fire each time the piston comes to the top of its stroke. They either use oil mixed with the fuel, or have a separate oil tank for oil to be mixed with the fuel as the engine runs. They can use carburetors or fuel injection, although the latter is only on recent models.
Four stroke engines have at least two valves for each cylinder, like a car engine. They fire every other time the piston comes to the top of its stroke. Lots more moving parts for the valve train. They use oil stored in a sump, like your car's oil pan, for all lubrication. Again, they can be carbureted or fuel-injected.
Two stroke engines are generally lighter in weight for their horsepower ratings. Four strokes are heavier, but quieter in operation, for the most part.
Some folks like one. Some like the other. Both work. Personally, I think four stroke engines have higher maintenance costs and are more expensive to repair when they do break.
Now, tell us what ouboards you're comparing. Year? Brand? That sort of thing.