To understand what each group believed, it is important to know how each group came to be. The Greek term "Sadducee" likely derives from the Hebrew term "Tzadoki", which is a form of the name Zadok (also literally meaning righteous in Hebrew). Zadok, the person, was the first high priest appointed by Solomon in the Hebrew Bible (1 Samuel 2). The Sadducees, along with the Essenes and the Oniads (two other sectarian groups during this period), traced their lineage to Zadok.

During the Hellenistic time period, Antiochus IV of the Seleucid Empire re-founded Jerusalem as a Greek polis, naming it Antiocha. As part of its re-founding as a Greek polis, a new high priest took power who was not part of the Zadokite family. This infuriated many Jews, including the Maccabees, who led a revolt, ultimately emancipating ancient Judea from Seleucid rule. After the Maccabees won their war, however, they retained both rule of the country and rule of the temple for themselves. Ruling the country was fine, but controlling the temple was not. This move established numerous sects who were opposed to a non-Zadokite high priest administering the cultic activities of the country. Two of these groups were the Sadducees and the Pharisees.

So the Sadducees were upset because their family no longer controlled the position of high priest, but how did the Pharisees form? There are a couple of suggestions, but instead of only choosing one as correct, it is likely an amalgamation of the two. First, since there was an un-authorized high priest, the Pharisees believed that the purity required to enter the temple precincts must now be maintained outside of the temple as well. Since the temple was no longer running as it should, this move made it so that temple purity must be maintained elsewhere. Second, when Antiochus IV re-founded Jerusalem as Antiocha, he exchanged the Jewish legal code (the Torah) for a Greek legal code. This was one of the last straws that set off the Maccabean revolt, and it is a move that effected a major move in the formation in the Pharisees. The Greek term Pharisee likely comes from the Hebrew perosh which means, "Set apart." During the Antiochene reforms, the Pharisees maintained that all Jews (i.e.: those living in Judea) must continue to keep the Jewish law. This meant abstaining from meat sacrificed to Zeus, from participating in the gymnasium, etc.

As part of the Pharisees code of laws, the concept of oral Torah was very prominent. This Torah, they believed, was one passed to Moses on Mt. Sinan and never written down (it was eventually in 200 C.E.). They accepted as their canon the entirety (as far as we can tell) of the books that comprise the Hebrew Bible today. The Sadducees on the other hand, only accepted the first five books, what is often referred to as the Torah or Pentateuch today. Because the Sadducees were originally a priestly group, they focused only on the books of the Bible that dealt with priestly rules. The rest were excessive. Working in the temple was a pretty nice gig. You make money, you eat a lot of food (especially meat), and you have nice accommodations for your family. There was no need to hope for things like resurrection or worry about prophetic works. What mattered was the maintenance of the Temple.

The Pharisees on the other hand, viewed themselves as outsiders. They were trying to convince Hellenistic Israel that the temple was corrupt and that the purity laws should be maintained at all times. For their message, they relied upon all aspects of Hebrew literature available. Possibly even some that does not appear in the Hebrew Bible today (ex.: 1 and 2 Enoch).

I hope this helps to clear up some of your questions! Josephus, a historian from the 1st c. C.E., discusses the formation of the Pharisees in Antiquities of the Jews, book 13, chapter 5. He also discusses the formation of the Sadducees shortly after he discusses the Pharisees.

You might also try /r/AcademicBiblical where you can get an objective look at this.

This seems like it's out of place for the goal of this subreddit, but /u/matts2 has a good suggestion for where to go.

If you have a question for how the Pharisees and Saducees compared politically, or how they were perceived, someone may come along to help. But as far as objectively analyzing their teachings, I think you'll be better off trying to farm that info somewhere else.