Loungewear as clothes for home
Short answer: Loungewear is clothing comfortable enough for the sofa and presentable enough to answer the door in. That is the difference between it and nightwear.
What sets it apart from nightwear
Nightwear is cut for lying down and often has a waistband meant to sit horizontally. Loungewear is cut for sitting and walking, with a waistband that does not dig in when you sit.
What makes it practical
A set you change into when you get home means your everyday clothes last longer and you do not sit in a tight waistband all evening. See bamboo loungewear for women.
The fabric
Bamboo viscose feels soft, does not restrict and does not get warm to sit in. Those are the three things that decide whether a set gets worn. See bamboo loungewear for men and bamboo sweatpants for women.
Frequently asked questions
Can you sleep in loungewear
Yes, but nightwear is better cut for lying down.
How many sets do you need
Two is enough. One in use and one in the wash.
Can you go out in it
To the postbox yes. That is the idea behind the category.