Here are some excerpts from the 1E version of the fantasy game. No specific alignments are given in the 1E book for the regular demons or devils. They are mostly "Evil (any)" or else they are labeled as "Selfish or Evil (any)". The Demon and Devil Lords and Ladies vary for both factions, so you won't find a "lawful" or "chaotic" divide. They simply hate each other.
From page 183 in between the sections on demons and devils:
Demons are known as the "evil ones" or "masters of darkness." They, like devils, are a powerful race of supernatural beings whose powers have given them the status of gods. These other-dimensional creatures view humanity as a plaything to satisfy their own decadent whims. They reside in the dimension called Hades.
Devils are also a race of strange other-dimensional creatures deemed by man as the forces of evil. They are known as "the tempters," corrupting virtue and all that is good. They will make forays from Hell to have a little fun in the Palladium world.
See religions and gods for additional details on demons and devils.
From the religion section on pages 154-155
Devils are strange other dimensional creatures full of evil and foul intent. Devils are worshipped by many as gods, particularly by trolls, orcs, goblins, hob-goblins, and witches. Devils, being a cruel, wicked lot, are the gods of jealousy, greed, hate, sorrow, pain, cruelty, theft, murder, war, disease, and all manners of evil and selfishness. Their attitudes, morals, and methods usually reflect their foul nature.
Alignments:Evil or selfish
Description:Varies from lesser, greater, and devil lords. Some appear as human or humanoid, others are hideous, others are half man half goat and/or serpent. Most are of red complexion, bear horns, tail, and claws. However, they can shape-change into any form they desire.
Followers:Clergy of gods of darkness and witches; greater devils and devil lords can endow the full range of clerical abilities. Also see Witchcraft.
Religion: Both restrictive (secret cults/covens/witchcraft) and expansive. Exclusive to devil pantheon; polytheistic.
Note: hates and opposes any connection with the gods of light and demons.
Demons are virtually identical to devils in nature and temperament. These other dimensional beings are renowned for their power, deceit, and ruthlessness. They are often worshipped by kobolds, wolfen, ogres, and orcs.
Alignments:Evil or selfish
Description:Shape and size vary greatly from spirits (like the jinn) to humanoid, to monstrosity. Some have heads resembling animals, most are of dark or black complexion.
Followers:Clergy of gods of darkness and witches. Greater demons and demon lords can endow the full range of clerical abilities. Also see Witchcraft.
Religion:Depending of specific sect of demon worshippers it can be both restrictive or expansive. Exclusive to demon pantheon and the Gods of Taut; polytheism.
Note:Hates and opposes the gods of light and devils. The devil and demon dimension (believed to be hell by most mortals) are two different dimensions. Demons and the gods of Taut exist in the same dimension/ world.
In that book, there were some lesser devils labeled as deevils or deevilkin. Later all residents of hell were renamed as deevils with the plane being renamed to Dyval. While Hell/Dyval is its own unique place, Hades is actually a twisted (larger scaled up) version of the Palladium (fantasy) world, with various demon lords ruling over various parts of it. I have no idea if that still holds true in Rifts though. This is all from the point of view of the fantasy setting, so maybe something in there will be of use to you.