Water and air are both fluids, but water is a lot "thicker" than air. In order to move forward, you need to push the stuff in front of you out the way. It's quite an effort to push a load of heavy water out the way, but air offers very little resistance. It is the viscosity of water that is in the way here, and we're talking about the physics of shear forces in fluids. Water is much more viscous than air, and is much more resistant to shear forces. Yes, water is a liquid, but air is a gas.
If you consider yourself trying to walk in the shallow end of a swimming pool and then walking normally in air, you have an accurate picture of what's going on. The aircraft engine(s) can develop enough trust to really tear through the fluid in which it is operating (which is air). Any "basic" contemporary military submarine probably has much more shaft horsepower than a jet fighter has thrust, but there is no way to get through the water anywhere nearly as quickly. And a submarine is not set up for speed in any case. It must "creep" through the water to avoid making sufficient noise to be detected.
planes
Supersonic plane
It's really fast. 340mps is not slow buddy. Very few planes travel faster than that :D.
It strictly depends on which two specific items you are comparing. Bullets travel various speeds, as do airplanes. Some bullets are faster than some planes, and some planes are faster than some bullets.
Of course not! A plane can travel at hundreds of miles an hour. The fastest horse only reaches 55 miles per hour for a very short distance. I mean, really! If horses were faster than planes, than why did we invent planes to travel long distances?
Supersonic planes travel faster than sound. There are a lot of them. Most modern fighter jets can do it, and there have even been commercial planes that could (eg Concorde, Tu-144).
A lot of stuff. Sound travels at 330 m/s (metres a second), so is faster than cars, planes (well, some...), and even Usain Bolt! However, some planes, and even the whip (so that's what that crackiing noise was! :) can travel faster. Of course, light is much faster!
Because they supposed to pass the atmosphere rather than just flying over the entire world.
Some people want to travel during the day, some want to travel at night, some planes travel faster than other planes, some planes fly a short distance, some fly a long distance. Sometimes the weather effects the way planes fly.
Some do, some don't. The bullet from a .45ACP is subsonic. There are a number of planes that fly at supersonic speeds.
They named as ultrasonic planes. They can travel very fast.
Flying is faster because the average speed traveled in a plane is greater than in a car and planes can travel along a straight line distance as opposed to being limited to streets and highways.