how do i compare rows in two different datagrids?

Hi, i have two different datagridViews. But both have two common columns. how do i compare all rows in both grids using the contents of one column as a primary key and comparing the value of the other column. plus how do i then move common rows into a new grid and all uncommon rows into another grid so i would have two grids - one containing matched rows and another containing unmatched rows? please i need this info urgently. thanks all, in anticipation.