Luxury implies comfort or quality.

Quality is not necessary for a good to be a luxury good. Only for demand to go up disproportionately with increases in income. Practically this means luxury goods are purchased to convey status. Consider Range Rover or Jaguar, which are known for being low quality but luxury brands.

Premium is the word that means paying extra for an increase in quality. Consider a Toyota vs a Kia.

These things are often correlated but don’t have to be.

>Only for demand to go up disproportionately with increases in income

Okay, if we want to limit ourselves to economics jargon rather than vernacular.

>Practically this means luxury goods are purchased to convey status

No, practically it means poor people aren't buying them much. Only some luxury good purchasing is related to status signaling.

>Premium is the word that means paying extra for an increase in quality

I'm not aware of a context where that would be the standard definition, though in some contexts it may be the excess portion of the price.

I don’t know what to tell you for you to believe me but premium relating to quality and luxury relating to status are literally the way they’re defined in the retail goods and brand world.

https://www.linkedin.com/pulse/difference-between-premium-lu...

https://medium.com/swlh/dont-confuse-luxury-with-premium-8-k...

https://imgmodelsblog.com/luxury-and-premium-comparison

Or, if you want to listen to techies talk about it, listen to this episode of Acquired: https://www.acquired.fm/episodes/lvmh