Traditional IRA: A Traditional IRA, if you are eligible, can be tax-deductible. The interest you earn on your money is tax deferred. (You don't pay taxes on the money until you withdraw it.)
Roth IRA: A Roth IRA is not tax-deductible, but the earnings can be tax-free. Also, there is no maximum age to open or contribute to a Roth IRA, so anyone who has earned income may open or contribute to a Roth IRA.
SEP: A Simplified Employee Pension (SEP) is for those who own a small business or are self-employed. Taxes are deferred until the time of withdrawal, and maximum contributions are greater than that of a Traditional IRA.
PLEASE CONSULT A TAX ADVISOR ON ALL TAX IMPLICATIONS.