There are birds that glide;
Albatrosses travel huge distances with two techniques used by many long-winged seabirds, dynamic soaring and slope soaring. Dynamic soaring involves repeatedly rising into wind and descending downwind thus gaining energy from the vertical wind gradient. The bird descends with the wind accelerating, then turns head to the slower wind over the water, climbing up to just before stall speed, the turn downwind again descending to accelerate with the higher altitude stronger wind and gravity. And so on. This maneuver allows the bird to cover almost 1000 km a day,
without flapping its wings once.
source
Albatross - Wikipedia, the free encyclopedia
FYI there are sixty-four species of flying fish and none of them are called a Bombay duck
Here's the Sailfin flyingfish
source wikimedia.org
And the Bombay Duck, Also called bummalo, Bombay Duck is a
marine lizardfish
source
http://www.bombay-duck.co.uk/background.htm
As you can see the fin structure is completely different, the Sailfin wing is oreintated horizontally and the Bombay Duck fin is oreintated vertically.
And the surface area of the fins of the Bombay Duck in relation to the body of the Bombay Duck is a lot smaller than that of the Sailfin flyingfish.
You evidently don't understand the mechanism of flight. Jet aeroplane and a propeller aeroplane both fly for the same reason that a glider aeroplane flys becuase the wing provides lift.
A bird can flap its wings till the cows come home but if the birds wings don't provide lift the bird will not fly, this is the same lift that the wings of a flying fish provide.
Your argument is wrong because it would be like saying glider aeroplanes are not planes because they don't fly like jet planes or prop planes because they don't use jet engines or propeller engines for flight.
So you are wrong there is no difference in flight and my claim that i made still stands unrefuted.