There are 2 types: real-time and final.
Real-time is used in interactive graphics and games where images must be created at a fast pace, for example, over 30 frames per second. This is a render that allows you to understand what the final version of the file will be like in the process of work. If you apply a color to the same object, the updated version will immediately be displayed on the screen.
At the same time, final renders are used, where speed does not matter. An unlimited amount of time is set for rendering, for pictures or videos.