The difference between economy class and the discounted basic economy class varies by airline, route, and plane type. Basic economy is typically the cheapest fare class offered by an airline.
The seats are the same as regular economy and located in the same cabin, but the ticket doesn’t include many of the amenities standard to regular economy like advanced seat assignments and complimentary upgrades based on airline loyalty status. Basic economy passengers typically accrue fewer loyalty points, have more restrictions on carry-on and checked luggage, and board last.