Is there a difference in transaction fees when charging a purchase as credit versus debit using the same card?

Answer 1

Yes, there are NO fees when charging with a credit card. Fees only apply to debit cards.

Answer 2

depends on the cards.

for the most part credit cards don't charge you per use, it's interest billed at the end of the month after the grace period.

debit charges typically per use, unless you go with a monthly plan.