We're not sure why Marvel decided that 'Ironheart' would make a better name for a female Ironman than simply calling her 'Ironwoman,' but that's the route they went down, and this is the look she ended up with. This is another 'alternate universe' creation, where child genius Riri Williams had to stand in for a while after Tony Stark was seriously injured and fell into a coma.
Stark would have approved of the choice if he'd been aware of it; he was already aware of Williams' brilliant mind after she invented her own Ironman suit. He took her under his wing as a 15-year-old protege, giving her his personal tutelage in how to become a superhero. As both characters are really just regular people in a suit, there would be nothing to pick between them in terms of ability. We guess it just comes down to a case of 'who wore it better?'