Molar mass is the formula weight of any compound or molecule, by simply taking the sum of the compounds' atomic weight.
for example you can take glucose, C6H12O6
its molar mass is 180.0634 g/mol = 6(12.01) + 12(1.008) + 6(16.00) = 180.156.
Whereas the molar ratio or mole to mole ratio is defined as the ratio between the compounds or elements in a reaction. So for example if you take the following reaction,
C6H12O6 → 6H2O + 6CO2
the molar ratio would be 1:6:6. In this you take the coefficient of each molecule. I hope this helps!