Letter shift
A word or phrase becomes another when one letter is shifted to a new position. Examples: trollop, roll top and Proust, sprout.
If the letter is shifted only one space (as in complaint to compliant), the puzzle is instead classified as a metathesis (which see).
If the letter is shifted from the beginning to the end of the word, the puzzle is a special type of letter shift called a head-to-tail shift.
In a reversed letter shift, a word or phrase becomes another when one letter is shifted to a new position and the result is reversed. Example: ignited, dieting.
In a progressive letter shift, one letter in the first word or phrase is shifted to a different position to create a new word or phrase, then a (usually different) letter in the second word or phrase is shifted to generate the third result. Example: Scantron, Scranton, Cranston.
A phonetic version of a letter shift is called a sound shift (which see).