Current-controlled vs. voltage-controlled devices — and why one's drive circuit won't correctly drive the other.
Both a bipolar junction transistor (BJT) and a MOSFET use a third terminal to control current flowing between the other two. Past that, the resemblance mostly ends. A BJT's control terminal — the base — is fundamentally current-controlled: a small base current Ib, pushed continuously into a forward-biased base-emitter junction, controls a much larger collector current Ic = β·Ib, and Ib has to keep flowing for as long as the device is meant to conduct. A MOSFET's control terminal — the gate — is fundamentally voltage-controlled: the gate sits on the far side of a thin insulating oxide, isolated from the channel, so once the gate-source capacitance is charged to the voltage that opens the channel, essentially zero steady-state gate current is needed to hold it open. The gate draws real current only transiently, while that capacitance is being charged or discharged during a switching edge.