There is no distinction between gravitational and inertial accelerations. General Relativity Gravitation binds matter to matter. Use geometry to describe the paths of objects moving through space. Only spacetime is observer-independent. Need to describe the geometry of spacetime .
Parallel lines stay parallel always.
Lines that start parallel can converge or diverge at some distance away. Moving objects follow straight lines. Greater spacetime curvature. Greater spacetime curvature. A freely falling object follows a curved path.