The EOMONTH function in Microsoft Excel returns the last day of a month in the past, the current month, or a month in the future. Whether you need to calculate end-of-month due dates, deadlines, ...
DATEDIF(), which means Date + Dif, is a compatibility function left over from Lotus 1-2-3 that Microsoft adopted in Excel version 2000, which is the only version that explains how this function works.