Missile has a precision guided system, while Rocket does not have a guiding mechanism in most of cases.
Many textbooks suggests the difference between Rocket and missile is just there application involved, it is a self-propelled system, while traveling inside the atmosphere termed as Missile, and beyond the earth's atmosphere it is called Rocket.
Missile essentially requires a guiding mechanism to hit the target pre-defined in air or Earth surface.
In some cases Rocket may also have a self guiding mechanism, when it is used to carry astronauts to a particular space station (at particular point in space) it needs to have guiding techniques, whereas in most of the cases just to throw a satellite out to the space establishing it to an orbit it needs not to have a guided mechanism, since in later case Rocket has no constraint related to its destination, that is positioning of the satellite, it can be anywhere in circumference of the orbit.
It is required to mention here most of the people elaborate this difference as the device which carries satellites into orbit is called a "Rocket" and a Missile is by definition a weapon with a payload.It is a common analogy but a wrong definition which does to cover engineering and technical aspects of system.
Quick Fact : If a rocket is launched from the surface of the Earth, it needs to reach a speed of at least 7.9 kilometers per second (4.9 miles per second) in order to reach space. This speed of 7.9 kilometers per second is known as the orbital velocity, it corresponds to more than 20 times the speed of sound.
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