in both cases light is reflected back in the same medium. So how we differentiate these terms?
In the case of simple reflection of an incident beam there's always a transmitted beam. It might propagate over a very short distance in the second medium due to absorption (like when the second medium is e.g. a metal), but it does propagate as the usual sequence of crests and troughs, and this propagation is definitely directed away from the surface (although possibly at an angle).
As you increase the angle of incidence, the refracted beam turns, until at the critical angle of incidence the refracted beam becomes parallel to the surface. This is the moment when light no longer propagates away from the surface, instead propagating along it. This is the point where total internal reflection begins.
As you further increase the incidence angle beyond the critical angle, the transmitted beam becomes an evanescent wave, whose crests move, as in the case of exactly the critical angle, along the surface. The increase of incidence angle now makes the exponentials fall off more rapidly with distance from the surface.
This evanescent wave is the main difference between simple reflection and total internal reflection.