Except for punctuation, the Book of Mormon and the King James texts are identical, therefore, only the Book of Mormon text is quoted.
Although Isaiah notes that he saw things concerning Judah and Jerusalem (Isaiah 2:1), his vision includes references to three different peoples and two different lands. He speaks of Judah in the land of Jerusalem, of the “ daughters of Zion,” and of the “ branch of the Lord” in the land of Zion. The prophet Joseph Smith declared, “The prophets have spoken and written upon it [Zion]; but I will make a proclamation that will cover a broader ground. The whole of America is Zion itself from north to south, and is described by the Prophets, who declare that it is the Zion where the mountain of the Lord should be, and that it should be in the center of the land. When elders shall take up and examine the old prophecies in the Bible, they will see it” (TPJS, 362). Thus, the “ daughters of Zion” refer to those who inhabit the Americas.
The “ branch of the Lord” spoken of by Isaiah consists of those who are “escaped of Israel” (those of Israel who will have escaped the judgments which are to come upon the world in the last days). He speaks of these as being from the daughters of Zion and from Jerusalem. Therefore, the three peoples include the inhabitants of Jerusalem in general, the inhabitants of Zion in general, and the specific group from Zion and Jerusalem who constitute the beautiful and glorious branch (Church) of the Lord. The two lands include the land of Jerusalem and the land of the Americas.
The Savior justified Isaiah’s inclusion of the Gentiles: “For surely he spake as touching all things concerning my people which are of the house of Israel; therefore it must needs be that he must speak also to the Gentiles” (3 Nephi 23:2). It was necessary to speak to or about the Gentiles to show all things concerning the house of Israel. It was also necessary to speak to or about Zion to show the ultimate destiny of Judah. An understanding of that ultimate destiny of both branches of Israel will cause all of Israel to “lift up their hearts and rejoice for all men.” This validates Nephi’s purpose for including Isaiah’s words in his writings (2 Nephi 11:8).
Isaiah’s vision centers around the restoration of the gospel, the Second Coming of Christ, and the ushering in of his Millennial reign. It also includes prophecies concerning Judah in Isaiah’s own day. Since it is a vision of Judah and Jerusalem, this would be expected.