What is the defference between ordinary annuity and annuity due?

What is the defference between ordinary annuity and annuity due?
In an ordinary annuity, the payments are fed into the investment at the END of the year. In an annuity due, the payments are made at the BEGINNING of the year. Therefore, with an annuity due, each annuity payment accumulates an extra year of interest. This means that the future value of an annuity due is always greater than the future value of an ordinary annuity.

When computing present value, each payment in an annuity due is discounted for one less year (because one of the payments is not made in the future- it is made at the beginning of this year and is already in terms of present dollars). This will result in a larger present value for an annuity due than for an ordinary annuity, as well.