Factors
Numbers which divide exactly into a higher number
are said to be factors of the higher number.
For example 2 x 3 = 6.
 2 and 3 are factors of 6

If you work out the factors of two
different  numbers the highest common
factor (HCF) is the highest number  that appears
In both lists

Prime Factors

The prime factors of a number are the
prime numbers which when multiplied
together  produce the number
For example the prime factors of 12 are
2, 2, and 3 (check 2 x 2 x 3 =12)
Try this