Conceptually then what is the difference between the Q and the wizards in Potter other than the Q don't use magic wands and/or conjur up 'magic,' with incantations that are an off take from ancient Latin?
Often it's just a matter of terminology. They're both storytelling tropes, but how you characterize them depends on what kind of story you're telling. A lot of the things in Harry Potter
could've been done almost identically in a near-future SF setting -- things like animated photographs in newspapers or the Marauder's Map are only a few years away in real life (and frankly I feel a little sorry for Rowling because the next generation of kids reading these books is going to wonder what's so magical about a lot of this stuff that's just like what they see around them in reality). But Rowling chose to cast them in the context of magic because that's the kind of story and setting she chose.
Still, I guess the deeper difference is in the assumptions being made about the underlying source of the phenomena. Stories about magic generally assume that the source is supernatural or divine and is fundamentally unknowable or inexplicable -- or at least, in universes like Potter or Duane's Young Wizards where the sorcery is systematized and formalized like a science, that it's something special and set apart from the mundane world, something only certain individuals are able to perceive or tap into while most normal folks are excluded. Either way, it's treated as something intrinsically separate from the normal, natural world. Whereas in science fiction, the assumption is that no matter how extraordinary the power is, it's nonetheless rooted in the normal laws of the universe and can be achieved by anyone with sufficiently advanced technology or sufficiently evolved mental ability. True, in a lot of stories, that difference is just in the background and doesn't bear on the events of the story, so in those cases they're effectively interchangeable; but there is a difference in the underlying assumptions about the type of world you're depicting.