what are the differences between te deum laudamus and dies irae

Te Deum laudamus, (Latin: “God, We Praise You” )also called Te Deum, Latin hymn to God the Father and Christ the Son, traditionally sung on occasions of public rejoicing. According to legend, it was improvised antiphonally by St. Ambrose and St. Augustine at the latter’s baptism. It has more plausibly been attributed to Nicetas, bishop of Remesiana in the early 5th century, and its present form—equal sections devoted to the Father and Son, a half-clause to the Holy Spirit, followed by a litany—fits in historically with part of the Arian controversy (over the nature of Christ) of the 4th century.  HOPE THIS HELPS