These terms pertain to the parts of an author's name.
APA reference lists are arranged alphabetically according to the main author's surname(s) followed by the initials of their first name(s).
Example—reference list entry (partial)
Stevenson, R. L. (1908)
It is sometimes difficult to distinguish between a middle name and two unhyphenated surnames (for example, whether author David Foster Wallace ought to be referenced as Foster Wallace, D. or Wallace, D. F). Here are some tips to help with this:
Tips
Example—bibliographic record & reference list entry
Stevenson, R.L. (1908). In the south seas. Retrieved from ProQuest eBook Central Database.
Terminology—a brief explanation of terms in this section
Sentence case
The way this sentence is written, beginning with a capital and all other words in lower case (unless proper nouns, e.g., New Zealand).
Title case
When Each Word In a Title or Sentence Begins With a Capital Letter Like This (Except Words Less Than Four Letters Long).
Note: In reference list entries, the word that follows a colon [:] should begin with a capital letter.
Books
The title of a book should be italicised and written in sentence case.
Example—reference list entry
Wallace, D. F. (1999). Brief interviews with hideous men. New York, NY: Little, Brown.
Chapter in edited book
The rules for book titles (above) apply. However the title of the book chapter is not italicised and is written in sentence case.
However, if the title of the chapter contains the title of another work, the latter should be italicised and written in sentence case.
Journal articles
The title of the journal is italicised and is written in title case. However, the title of the article itself is not italicised and is written in sentence case.
See also in this guide: How do I reference a resource that lists no author?
Take heed of the slight variation to the above rules for in-text citation of resources with no clear author(s).
When directly referencing 2+ authors in text, use and (as this falls within your regular sentence).
Example—in-text citation
According to Jones and Smith (2018) ... (p. 33).
When indirectly referencing 2+ authors within parentheses use &.
Example—in-text citation
... (Jones & Smith, 2018, p. 33).
American Psychological Association (APA). (2010). Publication manual of the American Psychological Association (6th ed.). Washington, DC: Author.