From your question, the general category of characters or symbols that you are referring to are called Whitespace Characters.
Whitespace characters are the representation of any character that causes a horizontal or vertical spacing change in typography.
The symbols themselves are called markup symbols and stem from proofreading editor markup symbol sets. See the graphic below for one of many examples on the web of proofreading markup.
In the case of the characters you are asking about specifically. These are a symbolic set that Apple chose to represent the whitespace markup for their system. Different OSs have chosen to represent some of these characters differently. This is typical of systems that don't understand where these symbols came from in the first place.
The second one in specific is the Nonbreaking space, and was chosen because the classic proofreading markup for a space was a #. Since the # character is a real character and used in computer designations, a newer character had to be created. On some OSs this is represented as a larger dot with a smaller dot above it, rather than the caret or circumfex symbol.
In terms of old school typography the character is the Em Space. The em space is a nonbreaking space equal to the width of a typeface's point size. It was derived from old typesetting where a blank metal block who's width is that of a capital M was placed in a row of text. This is also where the HTML/CSS designation for an "em" character sizing comes from.
