what is the difference between " AT " and " ON "

AT is used for a certain point in time. ex: at 3.45p.m, at noon, at midnight, at sunset, at night. - for a particular house or place ex: he stays at apsara hotel. - for villages and smaller twons. - for a particular place for work. ex: sheela works at Google, sushan works at the General hospital. ON is used for specific day * date, day of the week, special day. he came on Friday, pooja was born on November 19th, 1999.