Well, well, we all don’t notice if the difference between “father” and “dad”.
They are not just a noun, it look similar in the outside but definitely difference in the inside.
To judge a man whether he is a father or dad, we must observe his surrounding (his family, his friends, and other relationship) NOT JUST BY APPEARANCE!
If your family think you are a responsible dad, then you will know how to be a competent Dad. If you are a guy who let your mom to take care of your child In order to have a drink with your drinking buddy, then you will be the child father, but not dad.
If you see a child with an endless joy when contemplate his father , and believe in himself that his father will make his life better, then this father must be the child dad, not a father.