In the Avengers: Age Of Ultron, Ultron was portrayed as a weak villain but in the comics he is one of the deadliest villains of MCU.
In the movie it was shown that Thanos was killing half of the universe so that others can live happily but in comics he is more into rage and loves Death.
Scarlet Witch is one of the most powerful Characters in marvel but in the comics when it comes to personal life she has been the deadliest evil.
The world war hulk who was in the rage to destroy the world was shown weak in the MCU movies and compared to the comics.
Zemo in the comics is a great tactician and hand-to-hand combatant, who was able to give competition to Captain America but in the Civil War he was a failed Villain.
Vision has a mind stone and in the comics he dominated the character but in Infinity War he was one of the useless characters.
Black Widow was one of the original 6 Avengers who was introduced but after Age of Ultron the character was wasted according to her capability.