Manual v aperture priority

Hi- is there any difference between setting aperture priority, as opposed to setting the aperture on manual and then pressing the AE-L button (on the K100D)? Many thanks.

Theres not much difference in any of the various ways to get the exposure right, regardless of the mode it all come down to the correct balance of aperture, shutter speed and ISO rating, the various exposure modes simply allow users to choose the method that suits them best and assists with the type of subject. ie using shutter priority mode for action photography or aperture priority for landscape or portrait work where depth of field is all important. but that doesnt limit a sports photographer to using Tv mode, he could simply use either manual or Av and just make sure the shutter speed was kept high by setting larger apertures

In your case, pressing the AE button in manual will revert the camera to AE mode where the camera sets what aperture value and shutter speed it thinks best, aperture priority give you full control over setting the aperture.

Thanks. Now I understand!