The ending of the Haikyu manga sees the main characters having accomplished their goals and leaving a lasting impact on the volleyball world. It wraps up their stories in a satisfying way.
The Haikyu anime follows the manga pretty closely. There are only a few tweaks here and there for better animation or to make it more suitable for the screen, but the essence remains the same.
The Haikyu anime adheres closely to the manga. The characters' personalities, the key events, and the overall tone are all preserved. Though there are a few changes here and there, they don't significantly deviate from the manga's essence.