How to understand credit- and debit cards? (more info inside)

I’m almost turning 18 and I have to admit that I’m not quite sure what the definition of a credit- and a debit card is.

To me a credit card is -> the card used for mostly payments. i.e, if I were to buy something from a store, I would ‘pay’ with my credit card and later I would receive a bill to my account and pay that bill straight from my bank account. This is a sort of ‘borrowing’ in that sense.

But with a debit card -> when used in payments, you pay straight from your bank account… that money that you pay with is withdrawn from your account.

That’s the way that I think of the whole credit and debit cards. Is it right… because I understand it this way. Please when you explain to me the definitions and how these things all work, could you try and make it as easily understandable as possible.
Adding to that, I’m studying business (you can call it ‘majoring in business’) so I’m expected to know this but please, no mean comments.

And I’m asking this because my parents and I were talking and I got confused on what sort of cards I own so my stepfather said to me: “you call yourself a business student, yet you don’t know the difference between credit card and debit card”. He truly hurt my feelings and most of you know that sometime back I asked a question concerning my future and that he wasn’t very supportive of what I’m doing because he thinks that I’m just learning this because that’s what my mother is currently studying at the university.