Sigh. Is this that hard to look up?
MD5 Password: well basically it is a password that is hashed with the MD5 algorithm. The hash is used to compare with what the user puts in as the password. So if the user puts in "password" and the hash comes out as "12jlkjaax854308543098djajdfk" it should match the one for the user in the shadow file. This technique is commonly used on *nix platforms. There is also a salt added to ensure that if a user has the same password as another the hash will not match (makes it harder for an attacker to pick out).
Crypt hex: Well, crypt is a password encryption function. Hex usually refers to hexadecimal but I can honestly say I've never seen the two together. Perhaps we can have a better example of where you saw this combination.
Sources of reference:
crypt reference: man pages (slackware 9.1 machine)
md5: man pages (slackware 9.1 machine)
password: common knowledge.