From a related word or phrase: This is a redirect from a word or phrase (term) to a page title that is related in some way. This redirect might be a good search term, or it could be a candidate for a Wiktionary link.
Redirects from related words are not properly redirects from alternative spellings of the same word. They are also different from redirects that are subtopics or related topics, because unlike those, a related word or phrase probably does not warrant its own subtopic section in the target page or possess the possibility of ever becoming an article, template, project page, and so forth.
To a related topic: This is a redirect to an article about a similar topic.
Redirects from related topics are different than redirects from related words, because a related topic is more likely to warrant a full and detailed description in the target article. If this redirect's subject is notable, then also tag it with {{R with possibilities}} and {{R printworthy}}.