Yup. Roots and culture tends to have more emphasis on the message in the music, usually focusing on Rastafari, social issues, or similar themes. Bob Marley, Peter Tosh, Bunny Wailer, some of The Meditations, Jacob Miller and Inner Circle, Culture, most Black Uhuru, Everton Blender, Israel Vibration, Burning Spear, and others are examples of roots (although Everton has some dancehall flavor to his music, and The Meditations also do some lovers' rock).
Lovers', like you mentioned, is more soul/R and B based in terms of romantic themes. Gregory Isaacs, some Dennis Brown, some Meditations, Freddie McGregor, and a few others I can't think of are examples of this.
Rockers' has more emphasis on a rock sound in delivery of the music, especially in terms of tempo, soloing, and riddims that aren't as laid back. Steel Pulse, Mystic Revealers, most of John Brown's Body, Rising Lion, and even Ziggy Marley (to me, at least) could be considered from the rockers' camp.
Of course, all the groups I mentioned don't always follow the breakdown I gave, but hopefully it'll help in terms of recognizing different aspects of reggae.
Happy listening...
