Can somebody help me to figure out whether 2 and 3 have different meanings ?

Q :

Consider 4 vowels (including a) and 8 consonants (including b)

1)How many 5 letters "words" containing 2 different vowels and 3 different consonants can be formed from the letters ?

2)How many of them contain 'b' ?

3)How many of them being with 'b' ?