What is thr difference between dividing 16 by 2 and finding the square roots of 16?

When you divide a number by two, you find the number that if you add it to itself, become the original number. 

When you square root a number, you find the smaller number that becomes the bigger number if you multiply it by itself.

For sixteen, if you divide it by two, you get 8, while if you square root it, it becomes 4.