WARNING: The following contains spoilers for Avengers #37 by Jason Aaron, Javier Garrón, Jason Keith, & VC's Cory Petit, on sale now.
The Iron Man and War Machine armors are similar -- after all, both were designed by Tony Stark, whose genius and technology have allowed him to create powerful suits of armor for himself as well as for his best friend, James "Rhodey" Rhodes. However, the big difference between the two is that while Stark wears the more "superhero" suit, Rhodes has an armor that is designed more for military combat. War Machine is the one with all the guns and rocket launchers and the shoulder turret, which is part of his signature look, and it's how the character is defined.
However, it turns out that Tony has kept all of the best toys for himself. Sure, he might have given Rhodey the big guns, but he held back others -- they're just better disguised.
In Avengers #37, Earth's Mightiest Heroes are locked in a battle with Khonshu, an ancient and powerful deity who has the combined abilities of Doctor Strange, Iron Fist and Ghost Rider but all of that power still isn't enough for the moon god. Khonshu is amassing power in a desperate attempt to prepare for a battle with Mephisto, and the deity has now set his sights on one of the most powerful weapons in the universe: the Starbrand, which has bonded with a baby girl who is under the care of Iron Man and Captain Marvel. Previously, the two superheroes took the child into space, to get her as far away from Khonshu as possible. However, the moon god has now found them.
Khonshu attacks Carol and Tony with everything he has, and the superheroes fight back, their primary concern being to protect the baby. Thankfully, they get a helping hand from Moon Knight, who is now powered by the Phoenix Force. Moon Knight knocks Khonshu away, but Iron Man takes his mission to protect the child very seriously -- especially when the Phoenix shows up. Therefore, he unleashes his armor's full arsenal to warn Moon Knight to step away.
As he does so, Stark reveals all of the weapons that are included in his latest Iron Man suit. Thanks to the use of nanotech, Tony employs a move that is extremely similar to what he does in Avengers: Infinity War. In the movie, Stark had a new nanotech suit that allowed him to create all manner of weapons that surrounded him when needed.
Here, the Armored Avengers pulls off the same move. In an instant, his suit is now completely surrounded by all manner of weapons such as missile launchers, laser cannons, machine guns, and rockets -- all weapons in the War Machine armor, plus much more. It's clear that Iron Man has just as much firepower as War Machine -- if not more, he's just not showing it off on every occasion.