Income w-2 what should the difference be between box 1 and box 3 and which should be a larger number?

On my W-2 my box 1 is greater than my box 3, but on my wifes w-2 box 1 is lower than box 3.   did someone load the wrong value into the wrong w-2 box?  So box 1 is wages, should that be all wages?  Box 3 says "social security wages" should this be wadges minus 401K contribution and oth non-taxable income?  Please enlighten me.  Thanks,