Bi manual vs checking for dilation

What's the difference between how a Dr exams a woman for a bi manual vs the way they would to check how dilated you are when having a baby?

The bimanual requires the second hand on the abdomen; in my experience, only one or two fingers are inserted for the dilation check, without the external hand. The dilation check is less lengthy, since it's only checking for one thing, while the bimanual is more comprehensive, including palpation of the uterus and ovaries.

In checking for dilation, the doctor only needs to put one or two fingers in the vagina and feel the cervix. You can tell how dilated the cervix is by placing your finger tips on it to see how big (dilated) the opening is. No fingers from the second hand are required to press down on the abdomen.