In the latest edition of Subtle Maneuvers, Mason Currey quotes the artist Charles Ray:
I don't see sculpture as a “practice”–I'm almost allergic to that word. My dentist has a practice; I have a behavior. For me the activity of making sculpture is a mental and physical behavior.
It prompted him to write "I'm not sure if I totally understand the distinction".
For me, the distinction between a practice and a behaviour is intentionality. A practice is something deliberate, repeated, steps towards something to be strived for, whereas a behaviour is automatic, instinctive, innate, just something you do as a matter of course.
Perhaps the goal is to so deeply internalise a practice that it becomes a behaviour, something as natural as breathing.
That's a good way of distinguishing it, Colin.
Although I can't remember who, I came across another artist who hated the word "practice". I think he just felt that it sounded pretentious and instead used the word "work". ("In my work I..." rather than "In my practice I...".) I think I tend to agree, but it doesn't bother me as much as it did him.
Similarly, many painters prefer to just call themselves painters rather than artists. A bit more down to earth.