In Mormon theology, our God is not unique. He is one of an infinitude of existing deities who are higher and lower than our God in the heirarchy. The four gods relevant to us are called The Father,our Heavenly Mother, Jesus, and the Holy Spirit.
—“And they (the Gods) said: … And the Gods pronounced… And the Gods organized… And the Gods planted…”[Book of Abraham 4:3, 10, 25; 5:8 (inThe Pearl of Great Price)] [Note: This continues all throughout the Book of Abraham]
• Joseph Smith (Mormonism's founding president-prophet): “I will preach on the plurality of Gods… The heads of the Gods appointed one God for us…” [History of the Church 6:474, 476]
• Joseph Smith (Mormonism's founding president-prophet): “A Council of the Gods. In the beginning, the head of the Gods called a council of the Gods; …” [Ensign (April 1971), 13-14.]
• Orson Pratt (Original 'Quorum of the Twelve' member): “If we should take a million of worlds like this and number their particles, we should find that there are more Gods than there are particles of matter in those worlds... One world has a personal God or Father, and the inhabitants thereof worship the attributes of that God, another world has another, and they worship His attributes...” [Journal of Discourses 2:345]
• Brigham Young (Mormonism's 2nd president-prophet): “How many Gods there are, I do not know. But there never was a time when there were not Gods and worlds, and when men were not passing through the same ordeals that we are now passing through.”[Journal of Discourses vol. 7:333]
• Brigham Young (Mormonism's 2nd president-prophet): “Consequently every earth has its redeemer, and every earth has its tempter; and every earth, and the people thereof, in their turn and time, receive all that we receive, and pass through all the ordeals that we are passing through.” [Journal of Discourses vol.14:71]
• John A. Widstoe: “God, angel and similar terms denote merely intelligent beings of varying degree of development. The thought, however, that there is a plurality of gods and other beings of varying grades, is a thought of fundamental truth.” [Rational Theology, 62.]
—“I have always declared God to be a distinct personage, Jesus Christ a separate and distinct personage from God the Father, and that the Holy Ghost was a distinct personage and a spirit; and these three constitute three distinct personages and three distinct gods”[Teachings of the Prophet Joseph Smith, 370.]
The difference between henotheism and polytheism is that, in the latter, more than one of the gods believed in are worshipped. All Mormons worship the Father, however some Mormons are polytheistic, worshipping Jesus as a separate God. Mormonism as a theology appears polytheistic, because the worshipping of Jesus is motivated not only by many Biblical scriptures, but also scriptures from the Book of Mormon. Consider:
1 Nephi 11:24 -- “I saw many fall down at his feet and worship him.”
3 Nephi 11:17 -- “they did fall down at the feet of Jesus, and did worship him.”
4 Nephi 1:37 -- “the true believers in Christ, and the true worshipers of Christ,”
It's also enough to say that Mormons teach that other Mormons on other planets ought to worship their respective deity, and ought not worship the God of Israel.