Bore=surface of the cylinder
Stroke=How far the piston goes into the cylinder.
Ill give you an example, if you do benchpress, lets say 145pounds.What is the easiest and the fastest way to make more reps?Large grip with 1 foot of going up and down or narrower grip with 3 feet of going up and down, i dont know for you, but id take number one option any time.It is more difficult to make more reps when you go further in the up and down motion .Another example, try to punch something, lets say air.Now punch the fastest you can go with 10 centimeters of margin and 50 centimeters of margin.If you can throw punches faster with a longer distance than with the short one, ill present you to the Inter-box group, they need your help.As you can see, doing quick small punches makes you go fast but the torque is missing, while punching slower but with a greater distance packs quite a "punch"(cheap joke).