Is it more energy efficient to use a crock pot for 8 hours or put something in the oven for 2 hours?

Hi Guys - I love using my crock pot but my husband and I are unsure which is the most energy efficient thing to do. Is it better to use a crock pot for 8 hours or to cook something in the oven for 2 hours. Let's say the crock pot is on the low setting and the oven (normal size oven) is at 325 degrees.