Question: what is the difference between number of moles and amount of substance?
Answer: The amount of a substance and number of moles are both unitless quantities (and the same thing). ... That is, 1 mole of (say) carbon atoms is about 6.02×1023 carbon atoms. Both have a dimension of 1 (the number one); a mole is conveniently represented as a unit of measurement but doesn't actually hold any physical meaning.