In slang|lang=en terms the difference between dog and fly
is that
dog is (slang) a man (derived from definition 2) while
fly is (slang) beautiful; displaying physical beauty.
In lang=en terms the difference between dog and fly
is that
dog is to follow in an annoying way, to constantly be affected by while
fly is to travel very fast.
In nautical|lang=en terms the difference between dog and fly
is that
dog is (nautical) to fasten a hatch securely while
fly is (nautical) that part of a compass on which the points are marked; the compass card.
As nouns the difference between dog and fly
is that
dog is a mammal,
canis lupus familiaris , that has been domesticated for thousands of years, of highly variable appearance due to human breeding while
fly is (zoology) any insect of the order diptera; characterized by having two wings, also called true flies or
fly can be (obsolete) the action of flying; flight.
As verbs the difference between dog and fly
is that
dog is to pursue with the intent to catch while
fly is to travel through the air, another gas or a vacuum, without being in contact with a grounded surface or
fly can be (baseball) to hit a fly ball; to hit a fly ball that is caught for an out compare ground (verb) and line (verb).
As an adjective fly is
(slang|dated) quick-witted, alert, mentally sharp, smart (in a mental sense).