What is the difference in formatting marks between Paragraph symbol, wider line spacing, and return symbol, a narrower line spacing, and how do make the difference?
You need to turn on View > Formatting marks to see the marks.
A Line feed, ↵ (U+21b5) is just a break in the line but is still the same paragraph. It is entered by Shift+Return.
A Paragraph break, ¶ (U+00b6 Pilcrow) is the end of a paragraph. If there is a spacing between paragraphs that is different than between lines within the paragraph then you will see a difference, this is defined by the paragraph style.
Probably worth reading up on styles. You can see what is contained within a style by right- clicking on it in the sidebar, selecting modify and seeing what is selected. A change here will affect the entire document. Cheers, Al
… just to amend: ↵ line break (as it’s called in LO) should be considered a manual override of automatic line break mechanism, where you are not satisfied where Writer breaks your line, and want it happen in a different place.