Your "Federal Income Tax" is the amount of tax calculated on your income and deductions for the year.  Federal Income Tax Withheld from W-2 is the amount of federal tax your employer took from your pay and sent to IRS.  The later amount goes to pay the former - your Federal Income Tax.  The amount withheld can be more or less than the amount of tax calculated.  The difference is either your refund, or the amount you owe.