This is a common question. These things can be a bit confusing.
A deduction is used to offset taxable income. For example, you have $5,000 in deductible mortgage interest and you are in a 15% tax bracket. This $5,000 deduction would yield a tax savings of $750.
A credit is used to offset actual tax liability. For example, you have a child tax credit of $2,000. Disregarding any limitations, this $2,000 credit would yield a tax savings of $2,000