Economy (also called coach or main cabin) is the most basic airline cabin: typically the lowest fare, with standard seat pitch around 30–32 inches, limited recline, and fewer included meals, bags, or amenities—especially on shorter routes.
Premium economy sits between economy and business class. It usually means a separate cabin with wider seats, roughly 38–42 inches of pitch, more recline (often with footrests), upgraded meals and drinks, and extras such as priority boarding or a checked-bag allowance. Perks and pricing vary by airline, but the cabin is meant to feel roomier than economy without business-class cost. (KAYAK)