Between the return from exile and 70AD, five major sects formed within Judaism: the Pharisees, Sadducees, Zealots, Essenes, and Christians. The New Testament was written by the Christians, mentions the Pharisees and Sadducees often, the Zealots in passing, and the Essenes by inference. Each group took as its focus an element of Judaism and built around it an ideology and way of life. Books could be/have been written on this, but here's my quick overview.
Due to their focus on the Jewish Kingdom, the Zealots despised the rule of the Greeks and later Romans. The Zealots looked to Phinehas (Exodus 6:25), the priest who drove his spear through a couple in the “act” of worshipping Baal at Peor. It’s this kind of zeal that lead to the group carrying daggers under their cloaks and staging an unsuccessful attempt at assassinating Herod. The Zealots were known to also use their daggers on fellow Jews who committed acts that they considered sacrilegious or unpatriotic. One of the 12 apostles was a Zealot - Simon the Zealot. Some had theorised that Judas was also a Zealot since his name, Iscariot, is thought to be a form of the word Sicarii who were the group of assassins within the Zealots. But, again, this is only a theory.
The Essenes focus was on the land God had given the Jewish people. Driven by the belief that all the other Jews had defiled the land, the Essenes separated themselves from the people of Israel and lived in isolated communal existence in the desert outside Jerusalem (possibly Qumran). Not a huge amount is known about the Essenes. We do know that they believed they alone had valid priests, observed celibate life, saw baptism as an important aspect of purity, and had very strict dietary laws. In 1947, a shepherd found a cave with jars containing writings from a group believed have a connection to the Essenes. These writings are known as the Dead Sea Scrolls. Many think that John the Baptist, due to his ascetic lifestyle and practice of Baptism, was at one time part of the Essene community. But again, it's only a theory.
The Sadducees were the priests of the Temple, and so had as their focus the Jewish Temple. An aristocratic group, they were very much more open to being Hellenized (“Greekified” if you will). They held a very literal interpretation of the written Torah (first 5 books of the Old Testament – the Law of Moses) and rejected any notion of an Oral Torah (a body of interpretation of the written Torah handed down from generation to generation.) And as the Gospels show, the Sadducees rejected the idea of a bodily resurrection. Since neither are mentioned in the Torah (believe it or not), there was no heaven or hell for the Sadducees. Instead, all who died eternally slept in to the abode of the dead, or sheol.
The Pharisees were what we would call today, a lay-movement. Their focus was without doubt the Jewish Torah. But the Pharisees not only considered the written Torah to be the word of God, but also the oral Torah. The oral Torah would be analogous to our Sacred Tradition (big “T”), and would centuries later be written down as what is now known as the Talmud. One was not born a Pharisee, they would choose to be a member. The Pharisees taught that the ritual purity was not something for the Temple priests (the Sadducees) alone, but that all Jews should observe it. And all Jews wishing to be righteous needed to observe all 613 mitzvot, or commandments found in the Torah. Though not spoken of in the written Torah, the Pharisees held beliefs about the afterlife based on what was found in the oral Torah. They believed the God punished the wicked and rewarded the righteous in the life to come, and that there would be a resurrection in the end. The Pharisees were also looking for a Messiah to come and establish peace and freedom to Israel. Paul was a fervent Pharisee before becoming a Christian, and his letters show this.
Christianity started out as a Jewish sect who focused on the Jewish Messiah - Jesus. From the beginning it didn’t see itself as a new religion so much as the fulfillment of Judaism. You can see this in the first big crisis of the Church, what Jewish laws the gentiles would be required to observe (read circumcision). The Council of Jerusalem (Acts 15) was called to address this problem. It was decided that the gentiles would only have to, “avoid pollution from idols, unlawful marriage, the meat of strangled animals, and blood” (Acts 15:20). Interestingly, Gentiles who met these criteria would satisfy Jewish purity laws just enough to allow Jews of that day to sit and eat at the same table with them. Why would this be so important? The early celebration of the Eucharist was in the form of a meal. Charging that the Christians fled instead of defending Jerusalem against the Romans (probably true since their focus was Christ and not the land or Temple), the ties between Judaism and Christianity were decidedly cut.
So, what happened to these groups?
The Zealots: After the Romans brutally put down a Jewish rebellion in 70 AD, destroying the Jewish Temple leaving only part of one wall standing (known as the “Wailing Wall”), the zealots stormed a Roman fortress known as Masada. Killing all Romans inside and taking fortress over, the Zealots were able to defend against a siege by the Tenth Roman Legion for nearly three years. Once the Romans did breach the walls of Masada, they found that the 936 Jews inside (men, women, and children) had committed mass suicide (can anyone say Jonestown?). Live by the sword, ….
The Essenes: After 70 AD, the Essenes seemed to disappear. Though no one is sure as to why, there are a few theories. One theory is that the Essenes had fixed a date on the coming of the Messiah. The date came, and left without any luck, and like the Millerites of the 19th century just dissolved after the great dissapointment. More likely is that they had lent their support to the Zealots in their war against Rome. Rome, not being very happy about this, let them know of their anger. Either way, the Essenes ceased to exists as they had before 70 AD. Not sure how long a completely celibate group could continue.
The Sadducees: With their focus on a Temple that no longer existed, work was hard to find for the Sadducees. While some weak data suggests the possibility of the Sadducees in some form making it to the medieval times, the overwhelming majority of historians place their end within a few years of the destruction of the Temple.
The Pharisees: With the focus of their faith on the Torah, and not tied to a physical entity (i.e. the land, kingdom, or Temple), the Pharisees were able to adjust to the events of 70 AD. They were able to turn the focus of their worship from the centralized Temple to the non-centralized synagogue. With the Rabbis and Torah (written and oral) leading the people, the Pharisees of Jesus’ time have become the modern day Jews.
The Christians: Modern day Catholics.