In case the tax words are confusing you, here's some general explanations of what the phrases mean:
TAX DEDUCTION - You get to not count this spending as part of your income.
TAX DEDUCTION Example 1: You claim the standard deduction for Married Filing Jointly of $12,400 for 2014. This deduction means you don't pay federal income taxes on $12,400 of the pay you and your spouse receive. If you didn't have this deduction and you were in the 15% federal income tax bracket, you would have paid $1,860 more in federal income taxes.
TAX DEDUCTION Example 2: You choose to itemize your deductions to claim a Mortgage Interest Deduction on $15,000 in interest payments. You *do not* claim the standard deduction, because you have to choose between the standard deduction and itemizing on your federal income taxes. Buy paying the bank $15,000 interest plus your principle/insurance/property-tax payments, you get charged $2,250 less on your federal income taxes. BUT you had to pay $15,000 in interest plus the other payments which might have been more than rent and you only got a $390 lower tax bill than if you had kept your interest money and used the standard deduction.
***UNASKED FOR OPINION***
Part I: I think a seeking a tax deduction is not a good way to make financial decisions. You generally have to spend more money than the tax deduction gives you to get the option of taking the deduction. Instead tax deductions are nice, small bonus for things you already do.
Part II: That said, I have a mortgage. It was a good idea for me for other than tax deduction reasons. The deduction is just a nice extra.
TAX CREDIT: A flat out gift from the federal government to encourage certain behaviors.
TAX CREDIT example: You are eligible for the Earned Income Tax Credit in 2014. You take it. The federal government gives you the full amount of the credit. (You were eligible because you are married filing jointly with no kids and have an adjusted gross income of $20,020 or less in 2014. So you get a gift of $496. No, you are not in the 15% tax bracket in this case.)