I got into a discussion recently with a friend about the differences between magic and technology, in the context of why I researched Galactic Age so thoroughly. Together, we made a couple of very interesting points, which I will summarize here.
I was the first to point out that in a lot of the more well-thought-out fantasy universes (including my own aborted Thinking About Fantasy series), arcane magic is really just that universe's form of technology: mages study the natural laws of their universe, which are logically consistent despite being radically different from our own, learn how they operate through experimentation and hypothesis (science), and then figure out how to exploit those predicable behaviors to bring the "forces of nature" under human control (engineering). So while the result is something that looks radically different from the real world's technology, it is fundamentally the same process.
Sam agreed, and mentioned that in a lot of "less-well-researched" science-fiction settings, technology operates more like magic: put a bunch of wires and glowy bits together, push some random buttons, and presto- it's a laser gun! Or maybe a microwave? We don't know, and don't bother trying to understand how it works, you're either a scientist who can make anything out of anything with the proper application of technobabble, or you're just hopelessly out of luck.
This was a major idea. But it doesn't tell the whole story. Yes, there's levels of logical consistency/intensity that span multiple genres, but those genres themselves are also qualitatively distinct things- "magic" and "technology" are more than just levels of nitpicking. That's why I've created a two-dimensional classification system: logical sense and nonsense are referred to as "hardness" or "softness", respectively, and are separate from what we will be discussing as our main point today: features of the "magical" as opposed to the "technological."
Basis: Probably the aspect of magic/technology tied the closest to hardness and softness is that of which physical laws the setting obeys. In hard technological settings, the physical laws of the fictional world are the same as ours, and soft technological settings at least put on an attempt to seem that way as well. In hard magical settings, however, the laws are often very, very different from ones that we are familiar with (no chemical elements or subatomic particles, maybe even no Newtonian motion), and in soft magical settings they likely do not exist at all. Seeing a hard setting, with radically different physical laws, that still looks technological, is very rare. However, this isn't a reliable metric because it can break down entirely in soft settings.
Objects Vs. People: It's surprisingly consistent: technology relies on objects to function, whereas magic needs human intervention. In a technological setting, even though a person is often involved in the process of doing Cool Things, what they do is operate and control a device that actually manipulates the powers involved. In a magical setting, generally you actually need a mage to be there, casting the spells, and the "equipment" that said mage uses is generally minimal. Occasionally in magic you will encounter constructs such as golems and enchanted objects that do Cool Things with little to no human intervention, but I guarantee you that said constructs will have been created by people, without the help of other devices.
Corporeality: Magic generally involves a great amount of incorporeal "glowy stuff": instant runes, summoning circles, beams of light, apparitions and puffs of smoke, that sort of thing. Even when physical objects are used, they tend to generate at least one of the above when active. Technology, on the other hand, tends to rely much more on matter, or physical structure. There's glowy stuff there as well, but it's almost always emitted by, contained within, or attached to a sizable chunk of hardware.
Accessibility: Tying into the corporeality and object/person dichotomies, technology can often be mass-produced to make it accessible to the everyday person. With magic, that is often not the case. Depending on the setting, magic may be vanishingly rare and disbelieved entirely by most people, but the most accessible it seems to get is to have some enchanted weapons, potions, etc. purchasable the general population, as well as occasional mages who are about as accessible as chip designers or other highly-educated professionals in a technological society. Any more than that, and the setting starts to seem like a hybrid of magical and technological rather than just more sophisticated magic.
Structure: In conjunction with the above, technology seems to generate new materials (especially metals) that fall into active use in the next generation of technology. Magical neomaterials are rare, and not often used for building.
Shape: One of the easiest ways to make something look magical or technological is the way it's shaped: technology tends to have either smooth lines or right angles with lots of geometric shapes, while magic is generally more squiggly. Except for circles. Magic likes circles for some reason.
Character Sets: This one is actually kind of strange, but oddly persistent. Technology tends to be numerical- everything encountered has measurements associated with it ("Warp core power at 53% and rising!"), science is done with math and equations, and of course computers spout nonsensical strings of binary if you so much as look at them funny. Magic on the other hand, is much more literary-based. There are of course a bunch of spells and spellbooks involved, but the instant runes are also, well, runes, the magibabble is much more object-oriented, and the standard image of magical research involves the wizard browsing through hundreds of old tomes in some arcane library (as opposed to the chalkboard-of-equations setup in science).