Beyond Rashi adding the names of the Nephilim in his commentary here, there seems to be a deeper, more essential change in how Rashi translates the word “Nephilim” in our verse:
In our parshah, Rashi says “who fell from the heavens.” However, when explaining the verse, “the Nephilim were on the earth,” Rashi says, “because they fell and caused the world to fall,” where “they fell” (simply) means that they were eliminated from the world (like “caused the world to fall” that Rashi says immediately afterward).
[There are commentators who explain that Rashi’s intention {in Bereishis} is that they “fell from the world, meaning from the Supernal world, referring to the heavens.” This would make Rashi’s explanation in Bereishis consistent with his explanation here of “who fell from the heavens.” However, this interpretation is problematic, since there is no indication of this in Rashi’s words. On the contrary, Rashi says both “they fell and caused the world to fall” in one continuum, as mentioned above.]
This is very puzzling: Why does Rashi differ from his explanation in parshas Bereishis and provide a new explanation, “who fell from the heavens”?
[For even with the {original} explanation of “they fell and caused the world to fall,” the spies’ emphasis {on the giants being} “from among the Nephilim” would still instill fear in the Jewish people. (This is especially true given Rashi’s second explanation for “men of the name {םֵשַּׁה}” — “men of desolation {מוֹןָמִּשׁ}, for they laid the world desolate.”)]
Furthermore: The change that Rashi makes in interpreting “Nephilim” doesn’t only describe a different manner of falling (whether they fell from the world or fell from the heavens) — it actually changes the definition of who the “Nephilim” were:
According to Rashi’s explanation in parshas Bereishis, the “Nephilim” were human beings (with no relation to angels or the heavenly realms) who “fell and caused the world to fall” through their sins. And this is how Rashi interprets (in his first and primary explanation) the words (there in parshas Bereishis) “sons of elokim.” Rashi explains that they were not angels, but rather were “the sons of the lords and the judges.”
In contrast, Rashi in our parshah explains that “they fell from the heavens,” that they were angels.
This is quite puzzling: Why does Rashi introduce this novel interpretation of “Nephilim”?
