What is the difference between Orthodox, Conservative and Reform Judaism, especially regarding Jewish practice?

I will answer you in short, as mandated in this concise framework. There is only one original Judaism, that which is loyal to the eternal Torah & halacha as codified in the Shulchan Aruch & the top halachic authorities in every generation. This is what's termed: orthodoxy. The Reform movement totally dismisses the eternal truth of halacha and belief (many of their leaders don't even believe in God), don't care the least about almost any Jewish Law, & can no way be considered Judaism. The "Conservative" movement is a little more complicated, for they theoretically pay lip-service to the classic sources, but play with them in a way that turn many, if not most mitzvot, into being irrelevant. Within the "Conservative" movement there is a very wide range of Jews, some who are close to Reform, while others (mostly the older rabbinic leaders, and surely not the average laymen), include Shabbat observers, and really Orthodox Jews who for various reasons, found themselves in the Conservative movement. The common denominator is that as a movement, they have practically no absolute Godly truth, and accordingly every community and individual really does what they want (including a very superficial conversion process, which is obviously totally unacceptable on a national level, & in the end, condones intermarriage), which is the exact opposite of an eternal Godly faith and nationality. The actions of the average Conservative laymen, who say keep kosher at home but not outside, speak for themselves, as do those who drive to synagogue, but not to business meetings, on the Shabbat. This approach turns the beautiful & eternal Jewish Law into mockery in the eyes of any intellectually honest person, and explain why today, so many of the Conservative who want to take Judaism seriously, end up being Orthodox. Regarding interaction with society, you cannot really identify most Conservative Jews (except for their "rabbis") and how much more so Reform Jews, apart from their gentile society, for they have assimilated so much, that the term "interaction" is superfluous. Regarding the Orthodox, there are different streams which vary greatly on this issue. In short, anyone born of a Jewish mother is Jewish, but Judaism is the Orthodox way.