As you can see, by comparing these popular lures to flies, they both do the
same thing. Both try to imitate bait fish and others forage like frogs. The
only real difference is that fly patterns are virtually weightless in
comparison to lures.
The weight of a lure is how an angler propels it to the target. With fly
fishing, we propel a feather light fly pattern to the target, except we use
the weight of the line. The simple mechanics of physics help us cast
virtually weightless flies, using a long rod combined with a weighted line.
Of course, the actual casting is part of the magical appeal of fly fishing.