The account of Enoch in the Book of Moses closely resembles The Book of Giants discovered at the location of the Dead Sea Scrolls (which would have been unavailable to Joseph Smith).
The Book of Giants mentions two groups known in Hebrew as the gibborim and the nephilim. This is interesting as Jeffrey M. Bradshaw notes:
In the Bible, gibborim almost always referred to a “mighty hero” or “warrior” and only later came to be interpreted in some cases as “giant.”Correctly understanding the distinctions among these groups is important because Joseph Smith specifically differentiated the “giants” from Enoch’s other adversaries.– Jeffrey M. Bradshaw – KnoWhy OTL05C — Could Joseph Smith Have Drawn On Ancient Manuscripts When He Translated the Story of Enoch?
This differentiation is found in Moses 7:14-15 which mentions two distinct groups including giants:
There also came up a land out of the depth of the sea, and so great was the fear of the enemies of the people of God, that they fled and stood afar off and went upon the land which came up out of the depth of the sea.
And the giants of the land, also, stood afar off; and there went forth a curse upon all people that fought against God;
How would Joseph Smith have known about these giants in relation to Enoch?