People use the words interchangeably, but they work differently and the gap is large.
Deductions
A deduction reduces the income that gets taxed. Its value depends on your bracket: a $1,000 deduction in a 22% bracket is worth about $220.
Credits
A credit reduces the tax itself. A $1,000 credit is worth $1,000 in any bracket. Some credits are refundable, meaning they can pay out beyond the tax owed.
Standard vs itemised
Itemising only helps when the itemised total beats the standard deduction. For most households it does not, which makes chasing small deductions a waste of time.
