An Explanatory Postscript is a short note added to the end of a document or letter that provides additional information or explanation. It is often abbreviated as an 'EPS' or 'P.S.' and is usually written after the main body of the text. An Endnote is a reference or citation that is placed at the end of a document, typically in a separate section. Endnotes are used to provide additional information about a topic or to cite sources used in the document.