In the comics, Iron Man did not kill Captain America. Their conflicts and battles were part of the storylines, but not to the extent of one killing the other. The relationship between them was complex but not fatal.
In the comics, Iron Man doesn't end up killing Captain America. Their battles and disputes have various outcomes, but not one that involves a fatal blow from Iron Man.
In the comics, Thanos defeats Iron Man through a combination of his strength, energy blasts, and strategic planning. It's a fierce and intense confrontation.