Difference between gram molecular mass and molar mass

[Ry122]

What is the difference between gram molecular mass and the molar mass?
My book says that the gram molecular mass of oxygen is 32 grams and the molar mass is 16. Since a mole is equal to the gram molecular mass shouldn't they be the same?

 

[bulldog23]

molecular mass of oxygen as a molecule is 32 grams because it is O_2. The molar mass is 16 grams for oxygen atom.

 

[Ry122]

What is O_2?

 

[Dick]

O_2 is a molecule consisting of two O atoms.