The annuity scheme assures that the total payment concerning a debt is equal for each period. Over the duration of the loan the interest being paid drops, and the repayment of the debt increases.
The linear scheme means the debt is divided by the number of periods to determine the repayment on the debt. Total payment for each period decreases as the interest is calculated over a decreasing remaining debt.
Repayment of the debt plus interest.
The amount with which the debt decreases in a period. The level of this repayment depends on the duration of the loan and the repayment scheme.