Question:What is the difference between gravitational field strength, g and the acceleration due to gravity (usually called the acceleration of free fall)?
These are both "g". g has a value of 10 near the surface of the Earth in both cases.
Only the unit is different. For gravitational field strength g=10N/kg, but for acceleration of free fall g=10 m/s/s.
This also means that the unit m/s/s = the unit N/kg.