Sadducees, Pharisees, and the Essenes – What’s the Difference?
The Hasidaeans, or "pious ones” were divided into three groups of religious extremists – the Sadducees, the Pharisees and the Essenes. In scripture, the New Testament does not mention the Essenes, probably due to their tendency to seclude themselves from other Jews, but that’s pure conjecture on my part. One thing that is known and demonstrated in scripture is that the Hasidaeans hated the Samaritans and considered them tainted, due to their inter-marriage with non-Jews and their religious worldview. The Samaritans accepted no scripture except the Pentateuch – the first 5 books of the Bible. This fact provoked the anger of the Hasidaeans, because the Samaritans rejected much of Hebrew scripture or the Old Testament, as we know it.
The Sadducees were a relatively small sect but held strong influence with the ruling priests. They considered God to be a distant ruler and were steadfast believers in free will. They didn’t believe in fate and felt that all the good or bad in human interaction was in accordance with personal will. They accepted only written scripture and rejected oral tradition. They also rejected the existence of angels, the afterlife and rejected resurrection from the dead. The Sadducees also were collaborators with their Roman rulers. The Romans favored this sect of Judaism for that very reason.
The Pharisees were a large and popular group with the people of Judea. They believed in both fate and the divine providence of God, but also believed that mankind had free will to affect their own fate. The Pharisees believed in and expanded oral traditions, as well as trusting written scripture. They also believed in both angels and resurrection from the dead. Their primary doctrinal stance emphasized purity and separation. If you didn’t believe what they believed, they didn’t want anything to do with you. They also did not like the Romans and openly denounced them and participated in mischief and open rebellion against the Romans, on occasion.
The Essenes were a small sect of Judaism that rejected everyone accept people from their own sect. They were not talked about much until the discovery of the Dead Sea Scrolls, which were found in the ruins of an Essenes enclave. They were the strictest sect and would punish people for the slightest transgression of the Law, by reducing their food ration. They shared everything like those in a commune, thus giving them the opportunity to punish people by withholding necessities. The Dead Sea Scrolls represent an Essene library. The scrolls reveal a community concerned with end times, in which it would be vindicated and would assume leadership over the temple according to Evans. 
 Craig A. Evans, "Christian Leaders Institute: Log in to the Site," Christian Leaders Institute, last modified August 18, 2015, https://moodle.christianleadersinstitute.org/mod/page/view.php?id=30515.
 “Pharisees, Sadducees & Essenes," Jewish Virtual Library, accessed July 27, 2018, https://www.jewishvirtuallibrary.org/pharisees-sadducees-and-essenes.