Here is the answer in physics. Smaller lighter pistons moved over a shorter distance (stroke) takes less for than a larger, heavy pistons moved over a longer distance, hence more RPM are possible, thus higher horsepower.
Now there are other factors make the RPMS usefull Vtec, 4 valve per cylinder etc. Both are great engines.
Bottom line you car does not car about brand, it matters how much HP is produced to push a given weight.
Rather than specific HP it is more interesting to talk about HP produced per pound of engine and how much total HP is avaible, that my friend is of use.
I know a civic si engine is powerful for its size, but who cares only 160 hp, I can not build a car light enough to capitolize on the light weight of the engine.