Psalm 77:20 (a) The people of Israel are compared to sheep under the leadership of the Lord GOD of Heaven. (See also Isaiah 40:11 - Isaiah 63:11; Jeremiah 13:17; Jeremiah 23:2; Jeremiah 25:34; Ezekiel 24:5; Micah 2:12; Matthew 26:31).
Luke 12:32 (a) This refers to the followers of the Lord JESUS. He is the shepherd, those who love Him are His sheep.
Acts 20:28 (a) In this passage the church is compared to sheep. It refers to the true church of GOD, consisting only of believers, born-again people. It does not refer to those great national and international organizations which call themselves "The Church." (See1Pe 5:2).