Abdul, who sits on the new US X Factor judging panel alongside the pair and ex-Pussycat Dolls star Nicole Scherzinger, told ET that music producer Reid is just as harsh on contestants as Cowell.
She said: 'It's fantastic. Simon's met his match with LA, you have no idea!'
But Abdul, 49, admitted that she still has a special relationship with the X Factor boss.
Talking about Cowell, she said: 'It feels beautifully uncomfortable. It's like a good, worn-in shoe on the wrong foot. It's like a good leather right-foot shoe on the left side.'