Hose ”sizes” are usually I.D., and the size has “some” relevance to pressures, but not at the typical pressures hydraulic systems operate (2K-3K).... size has more influence on VOLUME of fluid passed. A 3/8” I.D. Hose will actuate a small cylinder too rapidly for most purposes...and a 1/4” I.D. Will be slow to operate a large cylinder.... because of the volume of fluid pumped. The PRESSURE of the fluid affects the force-applied (As does the cylinder-piston surface area,...which is why a cylinder has more force in one direction than it can apply in the opposite, because the Rod takes up some of the piston surface area the side of the rod will have less work-capability.)