In Joel 2:28, the prophet taught that after a time of great destruction, “your old men shall dream dreams, [and] your young men shall see visions.” Many Mormons believe that this prophecy was partly fulfilled in the stories of Lehi’s dream and Nephi’s vision. But since it’s nearly impossible to date the writings of the prophet Joel (some scholars claim he was a postexilic prophet, while others place him as early as the ninth century BCE), this is hard to substantiate. Moreover, other key components of that prophecy (e.g., revelations to women and slaves) have no recorded parallel in this part of the Book of Mormon.
What is clear, however, is that the Book of Mormon makes a distinction between dreams and visions. Dreams are shadowy and a bit slippery; Lehi prefaces one recounting with “methought I saw” (verse 4), suggesting the uncertainty of the dream state, and conflates dreaming a dream with seeing a vision (verse 2). Lehi sees the Tree of Life in his allegorical dream, but Nephi, in contrast, is treated to the full vision and its symbolic meaning. He also is made to understand the importance of the future coming of Christ.