What is difference between a jet and a plane?

For understanding the working prince of a jet engine, first, we have to know about the propulsion of a jet engine.

Propulsion:- 

Propulsion means to push forward or drive an object forward. A propulsion system is a machine that produces thrust to push an object forward. On an airplane, thrust is usually generated through some application of Newton's third law of action and reaction. A gas, or working fluid, is accelerated by the engine, and the reaction to this acceleration produces a force on the engine.

The term jet propulsion refers to the action produced by a reactor to the ejection of matter. For example, when the matter in a typical rocket (like gunpowder in fireworks) is ignited, the resulting chemical reaction produces heat and gases, which escape from the rocket and cause it to move forward. The oxygen necessary for combustion is carried(in tanks or in a combined form) in the rocket itself on the air inducted into the engine to supply the necessary oxygen. After heat is released by the combination, the hot gases are accelerated through the engine so that the exit velocity is greater than the airstream velocity.

Turbojet:-

• It consists of the diffuser at the entrance which slows down the air (entering at a velocity equal to the plane speed)and part of the kinetic energy of the air stream is converted into pressure: this type of compression is called ram compression. 
• The air is further compressed to a pressure of 3 to bar in a rotary compressor(usually of axial flow type. 
• The compressed air then enters the combustion chamber (C.C) where fuel is added. The combustor fuels place at sensible constant pressure and subsequently, the temperature rises rapidly.
• The hot gases then enter the gas turbine where the partial experience takes place. The power produced is just sufficient to drive the compressor, fuel pump, and other auxiliaries. 
• The exhaust gases from the gas turbine which are at a higher provide a forward motion to the aircraft by the jet reaction (Newton's third law of motion) 

At higher speeds the turbojet gives higher propulsion efficiency. The turbojet are most suited to the rcrafts travelling above 800 km/h.

     The overall efficiency of a turbojet is the product of the thermal efficiency of the gas turbojet plant and the propulsive efficiency of the jet(nozzle).

• Ramjet Engine:-

• Ramjet produces thrust by ejecting a smaller mass of material at a higher velocity than do turbofan engines.

     Fuels contain a large quantity of potential energy, which is rapidly released during combustion. A portion of this heat energy is converted into useful work, moving the vehicle through the atmosphere or into the atmosphere. The very fuel-efficient turbofan engines used in modern commercial aircraft engines attempt to minimize the latter portion. To do so, impart a moderate increase in the mass velocity to the combustion products for the large mass of air drawn through the engine in a given time. But turbojet and ramjet engines, which meet more demanding supersonic flight requirements, are less fuel-efficient.

A pulse jet engine (or pulse jet)is a type of jet engine in which combustion occurs in pulses. A pulse jet engine a be made with few or no moving parts, and is capable of running statically(ie. it does not need to have air forced into its inlet typically by forwarding motion).

 Pulse-jet engines are a lightweight form of jet propulsion, but usually have a poor compression ratio, and hence give a low specific impulse. 

One notable line of research of pulse jet engines includes the pulse detonation engine which involves repeated detonations in the engine, and which can potentially give high compression and good efficiency.