None. That is the beauty of it. They are all infernal being. Ho, flavor text will give you a hint on how to play them but beyond that.... you're on your own. And often, the flavor text will be quite extensive and might be more than a page. Our two letters say way much and do give us a quick glance on how to play a creature. It is why the MM can have so many diverse monsters. Alignments remove a lot of texts that are absolutely necessary for systems without alignments. This in turn saves a lot of space that allows for more monsters/foes to be inserted in the book.In a game without alignments, what's the difference between a devil, a demon and a yugoloth?
This aspect is often overseen or handwaved by those who do not like alignment. It saves a lot of text.