As numerals the difference between twelve and three
is that
twelve is the cardinal number occurring after eleven and before thirteen, represented in arabic numerals as 12 and in roman numerals as xii while
three is (cardinal) a numerical value after two and before four represented in arabic digits as ; this many dots (•••).
As nouns the difference between twelve and three
is that
twelve is a group of twelve items while
three is the digit/figure 3.