difference between net force and resultant force
It is the resultant force because you calculate the resulting vector sum using the Pythagorean Theorem. It may or may not be a net force; it wouldn't be if there was another force of equal magnitude in the opposite direction.
A net force is the force you're left with when you add up all the force vectors; if they add up to zero, there is no net force.
A net force is the force you're left with when you add up all the force vectors; if they add up to zero, there is no net force.