The illustration I used to show: Compare the helicopter to an afterburning jet. The Helo generates enough lift to levitate the machine plus payload directly, using a pretty small engine. The rotor downwash velocity is low. But its Vmax is very limited.
The A/B jet can go like hell, because its exhaust velocity is astronomical; but it burns HUGE quantities of combustibles, and low-speed efficiency is terrible.
And all the other varieties of powerplants lie somewhere in between.