I remember a while back that JetBlue was advertising that their seats were more comfortable and that they were wider than the competition. Is this actually true, or was it just a marketing ploy?

Seatguru has JetBlue's A320 seats at 17.8" wide.
United's A320 seats are 18"

So, was it a clever marketing trick comparing JetBlue's A320 seats to a Boeing 737/757 series which has 17.2" seats (due to the design of the cabin)? Or are the seats really roomier?