What is the difference between the Hebrew words 'adam', 'ish' and 'enosh'? In Genesis, the word adam is used until the woman is brought to him and then he calls her 'Ishah' and refers to himself as 'Ish'. In Psalm 49;2 it refers to the sons of Adam and the sons of Ish. Who would then be the sons of Ish? Why this distinction? And in Genesis 18;16 the angels that visited Abraham are referred to as enosh in this verse.
The Torah generally uses 4 names for mankind, and Adam is the highest. There are 3 others that are gradually lower in stature (and therefore less of a compliment!):
The Alter Rebbe explains that Adam is the highest (it is based on the fact that it is similar to the hebrew word "adame" which means "similar to [God]" and sometimes represents mankind in relation to his or her intellect), whereas Ish is lower (and conotes the emotions). Still, these two terms are lofty terms referring to mankind as a lofty entity in or even the pinnacle of creation.
Rabbi Yosef Yitzchak Schneersohn explains that gever means a man who is accomplishing his tasks, a man of strength and mastery, but not in a spiritual sense, so this term is not a very lofty one. An enosh literally just means "mortal", someone whose biggest compliment is that they are alive... otherwise they are not contributing very much.
He also explains that Adam is indeed the pinncale of creation, in that he can relate to God better than angels, even the most lofty of angels, who - in their raw abstract intellects - are unable to conceive of a dwelling place for Hashem in a time bound, space bound, physical reality. Only Adam is able to conceive of this and make it happen.
The Zohar (III, 48a) explains that Adam represents the complete human being, male and female (so it can be used to describe man before Hashem split them, or a married couple who have achieved true intimacy). Once they are split apart, they are referred to as Ish and Isha.
I will see if I can find an answer as to why the angels are called enosh. That (and the rest) is a great question! Maybe it's because they were being described how they were meant to look - like vagabonds.