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Answer

Three most important words you must remember while analysing relative motions are " with respect to" . For example you are travelling in a car then any object inside the car is at rest with respect to you, do you see any of these objects move away or towards you? No, because they are at rest with respect to you. But at the same time your friend is outside the car so for him/her all the objects and the car are moving away from him/ her i.e. the distance between your friend and the car along with it's objects is increasing with time. Hence the car is moving with respect to your friend. I have assumed that your friend outside is standing still . But now if you delve further into relative motion and say your friend is moving at the same speed and in the same direction as the car then even with respect to your friend all the objects along with the car will appear at rest.

Answer

Speed is a scalar quantity while velocity is a vector quantity thus to state a speed you just need a magnitude i.e. some number while to state a velocity you need a magnitude as well as direction. For example a car is going with speed 100 km/hr but it's velocity will be 100km/hr east , where east is the direction. Hence using velocity one can state which direction an object is traveling along with it's speed, but with only speed we can't tell which direction the object is moving in.