The FET gates need to be driven with-respect-to their SOURCES.
If using high-side PFets, their sources are tied to +24V.
To turn them off, the gate has to be at 24V.
To turn them on, the gate has to be at 0 to ~15V.
If using high-side NFets, their drains are tied to +24V.
To turn them off, the gate has to be 0V.
To turn them on, the gate has to be > 30V, because the source is pulled all the way up to 24V. This is why it is easier to use PFets for high-side switching.
Note that to properly turn on any FET being used as a low impedance switch (motor driver), then the gate to source voltage must be 2 to 5 times the Vt. If Vt is about 4V, then it takes 10V on the gate to get the advertised Ron.