Art, Decoration, Design
This is merely an attempt.
We often use these terms interchangeably, but here’s another crack at the distinction drawn between art, decoration, and design. On a Venn diagram, these 3 circles may overlap, but they are not congruent.
Art provokes, decoration adorns, and design solves.
This requires an examination of the intention and the effect. Any of these things could be visually pleasing or messy or referential or affiliative to a particular group. But none of those things are a requirement. But if a visual thing doesn’t provoke, adorn, or solve, it may not be very good.
Example: A hotel painting. Is it art? Probably not. Not if it doesn’t provoke anything (except maybe dread or malaise). Does it fill a wall in the interest of some kind of aesthetic? Sure, so it’s probably decoration. Was it put there to answer a need to add calmness and sense of inoffensive homeyness? Yeah, so there’s an argument to be made that it’s design.
Not everything has to be art.