What is the difference between interest only and repayment?

Repayment Mortgages

With these kinds of mortgage, each month you pay back a portion of what you borrowed, plus interest, until the whole amount is paid off in full. Exactly how much interest you are charged will vary, but the broad structure of repayments remains the same for all repayment mortgages

Interest-Only Mortgages

These work slightly differently; each month you pay only the interest that is being charged, you do not make any contribution toward paying off the actual balance until the term of the mortgage is up, at which point you must pay off the amount that you borrowed in full. Therefore, these have much lower monthly payments.