Judo does not have different "styles" in the way that karate does.
Karate has distinctly different styles, schools or "ryu," and when Jigoro Kano founded the Kodokan in 1882, it was one "ryu" of jujutsu. In fact at that time there was probably not a distinction between karate and jujutsu as they were both unarmed (empty hand) arts and there were many names in use including Yawara and Taijutsu.
Kano changed the name of jujutsu to judo when he brought together many ryu of jujutsu under the one unifying principle of "maximum effeciency." The ju in judo and jujutsu represent the same concept of yielding to gain victory. But where as "jutsu" means "art" and referes to a collection of techniques, "do" means "way" which can be interpreted as guiding principle or "way" of life.
In Japan, Judo effectively replaced the older jutjutsu ryu. But abroad, some "jujutsu" schools exist to teach some of the techniques that have been eliminated from Judo.
Currently different Judo clubs may emphasize different aspects of Judo - ie sport vs self defense - or individual players may be said to have different "styles" in terms speed vs strength or being more proficient at groundwork vs standing techniques, but it is all Kodokan Judo.
Hope that explains it...