When I first got credit card, I wanted to use it to pay my telephone bill. But the employee at bank told me that I would be charged interest as withdrawing money when I did it in that way. I could do that without interest only when I have registered my credit card at Bell. So I paid by my debit card.

My question is that what's the difference between I purchasing or paying such bill by credit card. If I pay my tuition bill by credit card, will I be charged interest? Thanks.