1) Motion can be different depending on the relevant speeds or positions of the observer. For example, if you are riding in a car traveling at 20mph, a different car traveling beside you at 30mph won't seem to be going that fast because the difference in the two speeds is only 10mph. But if you are standing in one spot and a car speeds past you at that same speed, it will appear to be moving much faster than before because the difference between your speed and the car's speed is much greater.
2. You could describe is as linear motion if the car is traveling in a straight line, circular motion when the car is turning, and even rotational motion is describe the motion of the car's tires
