system
Given the following post, respond as if you're commenting on Reddit:
human
[Endgame] If the Quantum Nano suits could create Iron Man then why did the War Machine one have to be different?

All of the Avengers wore their quantum suits that looks functionally identical and form fitting to their body shape.  This includes Tony Stark's which became a suit of Iron Man armor when he needed it to.  So why was War Machine's suit so much bigger than the others?
gpt
Tony always saves the best toys for himself. This is partially due to paranoia - he wants to be able to take down any threat, even if that threat was once an ally - and part of it is simple pride.

The quantum suits the Avengers wore were not capable of performing the same functions as Tony's nanotech armor. There was some overlap, like the way the helmets form into place, but there's nothing to indicate that they could form weapons, fly, and so on.

So it isn't that Tony's quantum suit became the nanotech armor, it's that Tony's nanotech armor became a quantum suit. The War Machine armor is based on older tech, and can't become smaller when not in use, so the quantum suit that wrapped around it needed to deal with its actual physical size.