There's a lot of overlap and really, many things Harry does are combinations of elements. His Fuego rote nearly always has a "knockback" component, which clearly comes from spirit, even though he uses his blasting rod to control it and thinks of it as fire. Harry has perhaps read too many comic books, where "energy blasts" of various elements also knock enemies around. He controlled lightning from a storm and thought of it as "fire" but it likely also used a bit of earth (for magnetism/targeting) and air (for weather). Carlos might have managed that same effect a completely different way, focusing perhaps on the amount of water in the atmosphere and channeling the bolt through the conductive medium.
The answer is, any element can do anything in the realm of a mechanical attack, maneuver, block and to a limited extent (control shifts are hard) move. Harry, for example, has used Fozare on a number of occasions to give himself a "superleap" sort of power, but as he's crappy at control, it's always scary for him. Because Blocks are allowed, blocks against perception are allowed, although they'll manifest differently than the "spirit veil of invisibility". Fire could do very bright light, air or water might do fog, earth can raise a dust cloud....they all block vision, and probably interfere with enemy vision more than your own (as veil mechanics dictate) but the primary advantage of a spirit veil is that it's subtle (for that matter, Fozare type effects are a lot more subtle than ripping up the ground or manifesting tons of water that turn into ectoplasm later..spirit is subtle, that's its thing). If you're wondering how I'd use fire as a movement power, well, you can make ice bridges over water obstacles, or probably even turn your feet into ice-skates if you douse them in water first. If you're reasonably resistant to fire and abrasion you might even make an explosion that hurtles you in a direction. Spirit, earth or air are better for leaping about, and water for moving IN water, or surfing on water.
The details of what you do dictates which focus items you can use, whether refinement/specialization works, whether your aspects help or hinder and of course how likely it is for your opposition to counter it, or the environment to enhance or hinder it. The details also give hints to what fallout does, or what happens if a high shift attack misses its target and hits the environment instead.
