Ordinary
The parts of the Divine Service that (by and large) do not change from week to week.
Propers
The parts of the Divine Service that are “proper” to the individual day, including the Scripture readings, the Collect, the Psalm, and the hymns. These parts will always be different week to week.
Services of the Hours
Also known as the “Daily Office,” these are devotional worship liturgies especially designed to frame the singing of the Psalms. In the Middle Ages, monks would sing 8 of these services a day, one every 3 hours to fill the day. The services are as follows:
Matins - 12 a.m. - page 109 in the Evangelical Lutheran Hymnary
Lauds - 3 a.m.
Prime - 6 a.m. - page 108 in the Evangelical Lutheran Hymnary
Terce - 9 a.m.
Sext - 12 p.m.
None - 3 p.m.
Vespers - 6 p.m. - page 120 in the Evangelical Lutheran Hymnary
Compline - 9 p.m. - page 128 in the Evangelical Lutheran Hymnary
Today some of these services are used for midweek occasions, such as the additional devotions in the seasons of Advent and Lent.