As nouns the difference between stey and stet

is that stey is alternative form of lang=en while 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.

As a verb stet is

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