The 6 out front tells you to multiply 6 to the sum in the parenthesis, in this case being 12, so 6*12=72.
If you use the distributive property you are not going to add the 2 and 10 first but instead multiply the 6 to each of them separately and add last. So, 6*2 + 6*10= 12+60 = 72
You get the same answer just doing it a different way.