In Avengers Endgame we got to encounter two Thanos from different timelines. One was from the year 2014 and another one was from 2018. But, why did Thanos from 2014 seem more powerful than the Thanos from 2018? Here’s an answer to that.
The Thanos from 2018 was victorious and had completed his mission by snapping his fingers and wiping out half of all life in the universe. The Thanos from 2014 was in full conquerer mode and fought the Avengers at the Avengers Headquarters after destroying it. Well after watching Avengers Endgame people were posting all types of comments on how savage the younger Thanos was and how he almost seemed to be a better fighter that Thanos from 2018. Well, in Avengers Infinity War Thanos is going out of his way to not kill people and ultimately want the snap to decide their fate. When he is fighting The Avengers, he is only incapacitating then so that he is not biased in his approach in balancing the Universe. Whereas Thanos from 2014 is in full warrior mode and its a race against time. Thanos wants the Gauntlet and he would do anything to retrieve it.
That’s why when Thanos decimated Xander and got the first infinity stone, he knew he was one of the strongest beings in the universe. He was sure when he retrieved the space stone from Thor. This is when Thanos removes his armor as he knows that no one can beat him and he is the strongest being alive in the universe. This is not a theory and has been confirmed by Marvel’s VFX Supervisor. They said that they deliberately made the younger Thanos more ruthless and agile.