This is on the venue's website, though:
Is there reserved seating for concerts at Festival Pier?
NO, all shows are General Admission Seating and Festival Pier is 100% handicap accessible.
So, I'm taking it to mean there's seats, but as for who sits where, it's all up to who gets their first. If the lawn was GA and the seats assigned, I couldn't see (a) both those being the same price, and (b) the band putting no seats on their fan club presale.