The theory of relativity was given by Albert Einstein. The theory of relativity is derive into two parts that “The theory of special relativity” and “The theory of general relativity”.
The Special Theory Of Relativity
The special theory of relativity that describes by Einstein, It says that the speed of light is immovable and time is not Absolute and relying on gravity. The special theory of relativity was given by Einstein in AD 1905. According to Einstein, Speed of anything is not faster than the speed of light. Hence effects such as ‘Time dilation’ and ‘Length contraction’.
The General theory Of Relativity
The general theory of relativity that also describes by Einstein, It says that Gravity is not a force, but a curvature caused by Massive objects like the sun on space-time fabric. When an object arrived speed that close to the speed of light, Time slowing down for an object and when an object is in the field of very strong gravity like the black holes, Time slowing down for an object. The object in free fall cannot feel its own weight. This is the happiest thought of Einstein that created ‘The Equivalence Principle’. The general theory of relativity is proved that mass and energy are closely related. Hence E = mc^2.

Difference between Two Theories
The special theory of relativity is says that high speed is slowing down the time for object and mass can convert into the energy. The general theory of relativity is says that gravity is not an invisible force, but a curvature caused by Massive objects like the sun on space-time fabric.
Based on this theory, Earth creates curvature on space-time fabric and moon orbits around the Earth.

