The short distinction

FDY is supplied as a continuous filament yarn with a relatively smooth, oriented surface. DTY is texturised to add bulk and a different filament character. The finished fabric still depends on yarn specification, machine setting, construction and finishing.

What to ask

Do not specify only DTY or FDY. Share yarn count, filament count, desired cover, hand feel, stretch target and end use. A sample and production-card review are needed before treating a yarn choice as confirmed.