Is there really any difference between the words Pictography, Ideography, Symbols and Picture-symbols?

Question

I am currently absorbed in Megg's history for Graphic design and I came across certain terms that seem to have incredibly ambiguous meaning (Pictography, Ideography, Symbols & Signs) and one that doesn't even have a meaning at all (Picture-symbols). I have scoured the entirety of google to make sense of these words but I ended up finding myself in a blackhole of confusion.

After my research, I understood that:

• Pictographs generally describe simple pictures that lean towards simplicity
  
• Ideographs are pictographs but with a meaning different from the images or word. They are, more often than not, pictographs that are alluding to something that isn't tangible.
  
• Signs are marks used to describe a word or a complex notion

But then there are Symbols, which is a very confusing word.
According to Merriam webster:
A symbol is:

• something that stands for or suggests something else by reason of relationship, association, convention, or accidental resemblance
  
• a visible sign of something invisible
  
• an arbitrary or conventional sign used in writing or printing relating to a particular field to represent operations, quantities, elements, relations, or qualities
  
• a letter, character, or sign used instead of a word to represent a quantity, position, relationship, direction, or something to be done
  
• an object or act representing something in the unconscious mind that has been repressed.

So, I came to an unsure conclusion that both Signs, Symbols and Ideographs are represented pictographically but Signs and Symbols are a form of Ideographs.

Also, there is the compound word I mentioned earlier "Picture-symbols" that I don't understand. I searched google for that word but I arrived at a dead end, I couldn't find the meaning to that compound word. So, my assumption is "Picture-symbol" is just a word that's similar to the single word "Symbols"

Now, my question is: Is my conclusion and assumption right?

I attached an excerpt of the book for better context

Answer 1

None of these terms is truly standardized. For example, "ideogram" or "ideograph" is sometimes used to mean the same thing as "logogram" and sometimes used to mean something completely different, depending on the source.

Given the excerpt you posted, this author's usage seems to be:

• "Symbol" is a general term for a graphic that means something.
• "Picture-symbol" is a general term for a symbol that depicts something. The definition of "depict" here is pretty broad; the cuneiform symbol of a sun is very hard to recognize as such.
• "Pictographs" are symbols that mean what they depict. A picture of a sun means "sun".
• "Ideographs" are symbols that mean concepts related to what they depict, like the cuneiform picture of a sun meaning "light" or the hieroglyph of a sun meaning "day".

But, this is just a particular author's usage; I'm not aware of any standard definition of "picture-symbol" as a technical term, for example.