Without looking at your return it is impossible to know why.

These are the most common things that effect your refund or balance due:

• Different Filing Statuses;
• Dependents claimed;
• The amount of federal and/or state withholding;
• Income based credits, such as the Earned Income credit;
• Tax bracket changes

That is not even close to being enough information to answer you.  You have not told us your filing status, whether you have dependents, what credits/deductions you qualified for, how you earned your income (self-employed or W-2?) , how much was withheld from your pay........etc.etc...