How is weight different from gravity and how are they similar?

Weight is the force with which the body presses on the surface, the modulus is equal to the silt of the support reaction.
Gravity is the force with which the Earth attracts a body to itself, located on its surface or at some distance from it.
If the reaction force of the support is directed perpendicular to the surface, then the weight is directed against this force. They are equal in magnitude and different in signs. This can be easily observed by placing the forces for a horizontally moving body on some surface. In this case, in the absence of additional forces along the OY axis (top down / bottom up), then P (weight) = N (support reaction force) = mg (gravity)
If we consider a body located on an inclined surface, then N decreases, in fact, like P, since it will be necessary to project mg onto the OY axis, in this case directed perpendicular to the surface and co-direction. N.
We can say that weight is the force with which the body presses on the surface, due to the force of gravity. Weight can change in different situations (discussed above), with a constant gravity (it cannot change, because it is constant with a constant mass and gravitational acceleration mg)