BB non-iron and iron comparison

[Jay Gatsby]

I asked the lady at Brooks Brothers whether the fabric and buttons used on the non-iron shirts were inferior. I asked this because they seem to be phasing out the non-non-iron shirts for slim fit in the store by where I live. She told me that the buttons are the same, and she thought there was little difference in the fabric, minus chemical treatment. I remember reading on this forum that non-iron may have inferior fabric and buttons. Is there a difference?