GCF
The Greatest Common Factor (or the GCF) is the greatest real number shared between two integers. What makes this number a factor is that it is a whole, real number that two integers share –that is, when broken down to their lowest multiples, the largest integer that’s shared between the two numbers is their greatest common factor.
LCM
On the other hand, the Lowest Common Multiple (or LCM) is the integer shared by two numbers that can be divided by both numbers. Basically, in the list of two numbers’ respective list of multiples, the lowest number that the two numbers share is their lowest common multiple.