I did a comparison of the settings on the two ovens. What the 500 does not have that the 300 did were: broil, broiler steam and bread. What the 500 has that the 300 didn't is air fry, grill (replacing broil?), steam assistant (replacing bread?) And turbo roast. It also has a setting to add frozen to the toast cycle.
I hope I'm answering the questions you have. If not, please send me a reminder.