The Pharisees & Sadducees
By the time of the New Testament, a class of Priests known as the Sadducees had been established but the judges had disappeared.
The Saducees were aristocrats who followed a strict, literal reading of the Torah and had a Priestly tradition in the Temple. However they were also liberal in their attitudes toward the Greek culture of Hellenism.
The Pharisees were ordinary working people who had become concerned that the Priestly tradition of the Sadducees was wrongfully incorporating Hellenism. The Pharisees developed a method for interpreting the Torah without the Saducee Priests, called the 'Oral Torah'.
It's also useful to mention the Essenes. The Essenes emerged in response to the other two schools. The Essenes rejected Hellenism and also the Oral Torah but went to live a monastic life in the desert.
The Pharisees emerged as the successful bearers of the Jewish legacy and mainstream Judaism today is based on their ancient legal traditions. The disagreements about the Oral Torah between the Saducees, Pharisees and Essenes were never formally resolved.