You can use them both 
That's what I was getting at, just a different color, usually.Power steering fluid is ATF that they charge more for
There are BIG differences between power steering fluid and ATF. Many years ago my Dad had trouble with a customer's '67 Chrysler Newport that had noisy power steering. He worked on it for a while, changing the pump, box AND the lines. Finally he changed the fluid. He changed it from ATF to Chrysler power steering fluid, problem solved.