Pedant mode on:
Many people think nonstop and direct flights are interchangeable terms.
A nonstop flight does as its name suggests: flies from one airport to another without stopping. (One flight leg)
A through or direct flight, on the other hand, might consist of two or more flight legs.
Often, passengers traveling on direct flights make a stop at a midpoint airport and remain seated on the plane while some passengers exit and others board.