Difference between a membrane sweep and checking for dilation!?!?!

Im 38+2 and my midwife hasnt checked for dilation. She said she doesnt normally check until 40 weeks and that its painful. But i was under the impression that they just stuck a finger or two up there to check? And now im wondering if she thought i was talking about getting a membrane sweep? Cuz ive heard those arent too fun. I dont want to get a sweep, i just want to check for dilation. I go in Monday for my next appointment and they said theyll do it if i ask. Can someone please tell me what the difference is between the two?!?! FTM and I have no idea what to expect!!!