"We now know that there were many different sub-groups within ancient Judaism, and that the early "Jesus Movement" was just one of many different Jewish groups. ."
There are three main Jewish religious groups or movements that are currently active. The central tenants of Judaism are the basic building blocks of the religion. These movements have the major difference in the how and extent to which one keeps the laws of the Old Testament or Torah.
Judaism is what is termed an ethnoreligious group. In Judaism, one inherits their ethnicity through the maternal side of the family. However, one can convert to Judaism as their religion, without being ethnically Jewish.
The three main Jewish religious groups are: Orthodox Judaism, Conservative Judaism, and Reform Judaism.Orthodox Judaism is the most strict, requiring its' followers to keep the law literally, as is written in the Torah. Their keeping of the Law is done so strictly, without question. The laws or Torah are considered divine and eternal which means they cannot be altered.
Conservative and Reform Judaism are less strict in the interpretation of following the law (Torah). However, Conservative Jews tend to have a more traditional interpretation of the law than Reform Jews.
Reform Judaism views the Torah as more of an explanation and recommendation. The views of Orthodox and Conservative Judaism give the Torah the weight of Law, while Reform Judiasm is much more liberal in its' interpretation and practice .