BND stands for Bundesnachrichtendienst, which is German for Federal Intelligence Service. BND is Germany's foreign intelligence agency responsible for investigating threats to Germany from abroad, they perform basically the same service for Germany that the CIA does for the United States. The BND specializes in wiretapping and electronic surveillance of international communications to gather information on criminal activities like terrorism, weapons of mass destruction proliferation and illegal transfer of technology, organized crime, weapons and drug trafficking, money laundering, illegal migration and information warfare.
BfV (Bundesamt für Verfassungsschutz) or the Federal Office for the Protection of the Constitution is Germany's domestic intelligence agency. The BfV investigates domestic threats to the federal government of Germany, akin to certain aspects of the Department of Homeland Security. The BfV specializes in counter-intelligence, protective security, counter-sabotage and monitoring domestic terror groups like Neo Nazis, pro communist groups like the Die Linke and organized crime.