These are examples of what I think of when I hear the words "chant" and "hymn:" An example of Gregorian chant: "Dies Irae" https://www.youtube.com/watch?v=Dlr90NLDp-0 Hymn: "A Mighty Fortress Is Our God" https://www.youtube.com/watch?v=ADamVJaXZMg

Chant: (noun) a repeated rhythmic phrase, usually shouted by a crowd Hymn: (noun) a religious song or poem

A chant is a tuneless repetition of some words over and over (usually in a religious ceremony). A hymn is a religious song sung in a church.It has a melody,whereas a chant usually has no melody and is monotonous,and has only a few words that are just repeated.