Economy Class cabins are broken down into two categories. “Regular Economy” and “Premium Economy.” Economy Class seating is the most basic of accommodations.
F - First Class. G - Conditional Reservation. H - Economy/Coach Discounted – Usually an upgradable fare to Business. J - Business Class Premium. K - Economy/Coach Discounted.
If you're looking for the lowest price in American Airlines' main cabin, opt for the basic economy. These seats are basically just deeply discounted coach fares, and the restrictions aren't that different from the economy tickets. The main difference is that you can't choose your seat in advance.
More space, but not necessarily more comfortThe seats are an inch or two wider on average than the typical coach seat, and the rows are farther apart, offering several more inches of legroom. Most premium economy seats recline, and many have footrests. How much space you actually get depends on the airline.