As verbs the difference between stut and stet

is that stut is to stutter while stet is the act of marking previously edited material "stet" to indicate that something previously marked for change should remain as is.

As a noun stet is

a symbol used by proofreaders and typesetters to indicate that a word or phrase that was crossed out should still remain. This is usually marked by writing and circling the word stet above or beside the unwanted edit and underscoring the selection with dashes or dots. Alternatively, a circled checkmark may be used in the margin.