The biggest disadvantage of MOSFETs is their huge manufacturing tolerances. Where a bipolar transistor varies only minimally in its basis emitter turn-on voltage for a specified collector current, the gate source threshold voltage of a MOSFET can differ be several hundreds of %!

This is no real problem if you turn on the MOSFET by applying a gate source voltage of >10V. But if you have a digital circuit with MOSFET drivers running at 1,8V, this can mean, that the MOSFET cannot be fully turned on, if at all. Then you need a MOSFET, where the turn on resistance, source current or whatsoever is specified down to a gate source voltage of 1,8V.

"Logic Level MOSFET" means, that it is specified at a gate source voltage well below 10V. This can mean a Ugs of 4,5V, 3,0V or even 1,8V. But you must have a deeper look into the datasheet which logic level actually is meant.

"Logic level MOSFET" also means, that at a Ugs of 0V+x the MOSFET stays realiably turned off. "x" means "maximum output low level" of MOSFET driver.

Logic level MOSFETs aren't necessarily MOSFETs with tighter tolerances, or selected types, but more types with changed die geometries, to allow a lower turn on voltage and reliable turn-on/turn-off performance. But take care, this types often cannot withstand very high gates source voltages.

Kai Klaas