From the first movie, we’ve seen Captain America in many different suits. Some of them have been more effective than others, but each has a reason for its design. From a marketing point of view, each suit is meant to bring in more money for toys, action figures and Lego sets, while other suits also serve as callbacks to looks Cap has had before in other forms of media. From an in-universe perspective, every suit represents a moment of change for the character.
When the first film was released, Captain America wasn’t even a hero yet. He had just been rescued from the ice and was adjusting to the modern world. The movie’s costume design was meant to convey this sense of naivety and realism, while still showing off the heroism that the character is known for.
The next iteration of the uniform came in Avengers: Age of Ultron. In this version, the character steps into a more leadership role and begins working with other heroes to fight against the supervillains that populate the MCU. The new design is more utilitarian in nature, utilizing the same elements of the previous suit with minor improvements to make it look more modern.
This iteration of the suit also features a much more functional helmet, more reminiscent of real military gear than the star-spangled helmet from the first film. This more practical helmet marks a clear shift in Rogers’ character, showing that as the hero grows older and gains experience, he becomes more of a soldier than a star-spangled folk hero.