In Newtonian mechanics, both gravitational mass and inertial mass is m. This principle is known as the principle of equivalence. However, I heard that in Relativity, gravitational mass is γm instead of m because total energy of the particle is γmc2. But in special relativity, it is widely known that F=γ3ma while a is acceleration. Does that means inertial mass and gravitational mass is different in general and only approximately same at non-relativistic situation? Or is inertial mass also γm? Or is the answer totally different?