Musar על סנהדרין 215:17

The idea is to tell us that even though Noach was called איש צדיק תמים, this was true only in the generations during which he lived, i.e. בדורותיו. His righteousness was relative, when one considers the environment into which he had been born. Had he and his family not survived, the world would have been totally destroyed. The meaning of איש האדמה then is that his survival ensured the continuance of the אדמה, earth. It would have reverted to Tohu vavohu otherwise. Still, the word אדמה, severely limits Noach's achievement. The reverse is true of Moses. Even when engaged in the lowliest of his pursuits, the killing of the Egyptian, he employed the 42-lettered name of G–d. If he is called איש האלוקים (Deut, 33,1,and Exodus 24,13), it is because of his deep understanding of the names of G–d. Even when he killed the Egyptian he used this knowledge. According to the Ari zal the entire sojourn in Egypt and every event recorded of it, was under the heading of חידוש העולם, and the 42-lettered name of G–d was employed in creating the universe originally.