The difference between a large number of and a large amount of

Only countable nouns can be modified:

a large/ great/ good number of,

a good/ great many,

dozens of,

scores of,

quite a few 

Only uncountable nouns can be modified:

a great deal of,

a large amount of,

quite a little,

a large sum of

 

Modifies both countable and uncountable nouns:

plenty of,

a lot of,

lots of,

a large quantity of,

a good supply of