Gravity and the curvature of spacetime are closely related concepts in the theory of general relativity. Here's an explanation of their difference:
Gravity: Gravity is a force that we experience in our everyday lives. It is the force that attracts objects with mass toward each other. For example, it is what keeps us grounded on the Earth and what causes objects to fall when dropped. In classical physics, gravity was described as a force acting between masses according to Newton's law of universal gravitation. However, in the theory of general relativity, gravity is interpreted differently.
Curvature of Spacetime: According to general relativity, gravity is not seen as a force in the traditional sense. Instead, it is understood as the curvature of spacetime caused by the presence of mass and energy. In this theory, mass and energy curve the fabric of spacetime around them, creating a gravitational field. The curvature of spacetime tells objects how to move, and their motion is influenced by the shape of the curved spacetime.
In the presence of matter or energy, the curvature of spacetime determines the paths that objects follow. Objects move along the shortest paths, called geodesics, which are curved by the presence of mass or energy. The curvature of spacetime is determined by the distribution of matter and energy in the universe.
In summary, gravity is the force that attracts objects with mass, while the curvature of spacetime is the way that matter and energy curve the fabric of the universe, influencing the paths that objects take. In general relativity, gravity is not described as a force acting across space but rather as the effect of the curvature of spacetime caused by mass and energy.