For example, the definition given from the OALD for pronoun is the following one:


  a word that is used instead of a noun or noun phrase, for example he, it, hers, me, them, etc.


If I would rewrite it as the following, would the mean change?


  a word that is used instead of a noun, or noun phrase, for example he, it, hers, me, them, etc.


If the meaning doesn't change, are there other differences between those phrases? Is this just an example of using the Oxford comma, or is there something different/more?

I am asking because I rephrase a similar phrase, and I was said it was more correct without the comma.


Question: 'Bokeh' effect with autofocus switched off in manual mode (Nikon-D90)
Answer: If all the focus points are lighting up it's probably that all parts of the image are within the tolerance for the camera to consider them in focus. This is often the case with wide angle lenses and subjects of moderate distance from the camera. Essentially your depth of field is too large to be able to see clearly the difference between the in focus and out of focus parts of your image.

Achieving selective focus has been the subject of many questions here, but the short answer is to try:


focus on a really close subject
use the longest possible focal length (and shoot at the widest aperture)
use a really fast prime lens
use a full frame (35mm sensor) DSLR


in that exact order.