What is the difference between molar mass and atomic mass?

They are both have the same numerical value but what is the difference?

The molar mass is measured in grams. It is the mass of 1 mole of the substance.

The atomic mass is a relative measure based on the scale of 12C = 12.0000. It has no units. It is the mass of an average atom of an element compared to that of a carbon-12 isotope.

They are numerically the same, but represent different concepts.

The atomic mass of carbon = 12.011 (taking isotopes into account)
The molar mass of carbon = 12.011g

Also note that the molar mass of a substance takes into account the nature of the smallest particles.

Atomic mass of hydrogen = 1.01
Molar mass of hydrogen gas = 2.02g