what would be the engineering differences between and SI engine and a CI engine?

spark ignition and compression ignition?

doesn't the title tell it all?

did find this online:
1.Basically SI engines work on Otto Cycle and CI engines on Diesel cycle

2. SI engines use gasoline as fuel and CI engines use diesel as fuel.

3. SI engines use spark plugs and CI engines don't this is because the compression ratio of SI engines is small and the temperature developed is not high enough to start the combustion and so spark plug is used to initiate the combustion once the initial spark is generated the flame front takes care of the rest ,whereas in a CI engine the temperature generated is higher than the ignition temperature of diesel due to high compression ratio and so a spark plug is not needed.

4.The torque generated by CI engines are very high when compared to their counterpart SI engines this is because the CI engines at high compression ratio and so the piston travels far more distance into the cylinder and so the radius of crank also increases ,since torque is cross product of force and radius therefore this increase in radius causes an increase in torque ,the above is one of the many factors contributing to high torque of CI engines,and this is the reason why almost all the trucks and heavy vehicles use CI engines and passenger vehicles and bikes use SI engines.

5.Vibrations produced by CI engines is very high when compared with SI engines this is because of the high compression ratio used.

6. CI engines are heavy when compared to SI engines because of the need to withstand the high pressure developed ,the walls of the engine are made thicker to increase their strength and this one of the reason why Diesel engines are not usually preferred in bikes as they increase the weight of the bike and the vibrations make the ride wearisome.