Mach
Mach is a unit of speed. Mach is the ratio of a body's speed to the speed of sound in the surrounding medium, normally air.
Meters per second (m/s)
Meters per second (m/s) is the SI unit of speed or velocity. It represents the distance traveled in meters over one second.
It is used mainly in physics and engineering from describing the speed of a moving vehicle to the velocity of an object in free fall. It's simplicity makes it a good choice for describing speed and comparison with other units of speed.