Within Argentine tango there are various styles you may hear people refer to. They will say, "Oh, he's a milonguero dancer," or "She dances salon style." Styles are as unique as dancers and I think it's rather foolish to try to categorise either. Just remember if you hear terms like 'salon', 'milonguero', 'fantasia', or 'orillero' someone is talking about a certain style.
As with any evolving art form, trying to pin down the rules is impossible. Every day, new styles come forward and dancers find ways to play with them and incorporate them into their dance. In the past few years, styles known as 'nuevo' and 'liquid' have appeared. Who knows what's coming next? All we know is that it's coming.