portrait - What is the difference between 'P' mode vs. the scene modes?

Is there any difference between 'P' mode with appropriate settings (like aperture etc.) and a specific scene mode?

E.g., I wanna shoot a portrait. I can use 'Portrait' scene mode or 'P' mode with wide aperture (e.g. f/2.8 or so). Will the results basically be the same? I suppose a camera digital processor does mode-specific image processing in scene mode.

So is it always better to use a scene mode then 'P' mode for a medium-skilled photographer?

Update The question actually is about possible helpful image post processing is presented in scene modes but absent in 'P' mode. Is it possible to do settings in 'P' mode to obtain the same post-processing results?

Answer

It is highly dependent upon which camera system you are using. Although they are all similar in "P" mode, there are differences too. In the "Scene" modes all bets are off as there is more variety between different camera manufacturers.

In general, a scene mode such as Portrait might not only bias the camera towards a wider aperture but may also adjust the color/tint to render more pleasing skin tones. This is something the user would need to control themselves via color temperature and tint adjustment or the use of color profiles or "Picture Styles" when using "P" mode. In Landscape scene mode not only will a narrower aperture be selected but the color may be adjusted to give richer greens and blues. A Night portrait mode will not only use slow shutter sync to balance the background ambient lights with the flash illuminated subject in the foreground but might also adjust the Auto white balance to render the lights a little warmer.

Things such as JPEG or raw files, ISO, color, aperture (wide or narrow)/shutter (short or long) priority, sharpening, etc. are all controlled by the Scene modes. In P mode the user has control over many of them.

With most systems the use of scene modes locks out the user from selecting many options that are allowed in the "creative" modes": P, Tv, Av, and M. This even extends to the decision whether to save the raw data or let the camera go ahead and convert to jpeg before recording the image to the memory card.