As nouns the difference between loungewear and sleepwear
is that loungewear is loose clothing in which one can lounge while sleepwear is garments designed to be worn in bed; nightclothes.
loungewear
English
Noun
(-)
Loose clothing in which one can lounge.
sleepwear
English
Noun
(-)
garments designed to be worn in bed; nightclothes