[sandworm101]

A rocket is something with only an exhaust. A jet also has an intake. And it goes a little further than just not lifting the 02. Any unburnt gas (air) becomes a 'working fluid' that can be pushed. A rocket moves by throwing gas away at speed. Jets also grab gas from the air and accelerate it along with exhaust products. That's why a jet or turbofan can have a high specific impulse with such a low exhaust velocity, higher (>8k) than even an ion thruster in vacuum.