I've heard a lot of people talking about the two different semichahs that one might receive: יורה יורה ("Yoreh Yoreh") and ידין ידין ("Yadin Yadin").
What is the difference between them?
[Sourced answers preferred]
These two semicha 'tracks' cover different areas of halakah: Yoreh Yoreh covers areas that deal with the day to day questions that rabbis might receive, such as questions on kashrut or taharat hamishpacha. Most programs of Yoreh Yoreh also include study of the laws of Shabbat and Mourning. It's traditionally associated with the second section of Tur/Shulchan Arcuh, "Yoreh Deah".
Yadin Yadin covers the type of knowledge that one would need to adjudicate cases between individuals- either in monetary or marital laws. This is traditionally associated with "Choshen Mishpat" and "Even HaEzer", the areas of Shulchan Aruch that deals with monetary and marital laws, respectively.
See the Gemara, Sanhedrin 5a for the origin of the names of these types of סמיכה.
א"ל ר' חייא לרבי בר אחי יורד לבבל יורה יורה ידין ידין יתיר בכורות יתיר....יתיר בכורות אל יתיר