Bundesstraße
One distinguishing characteristic between German "Bundesstraßen" and "Autobahnen" is that there usually is a general 100 km/h (62 mph) speed limit on federal highways out of built-up areas, as opposed to the merely advisory speed limit ("Richtgeschwindigkeit") of 130 km/h (83 mph) in unmarked sections of the autobahns. However, a number of "Bundesstraßen" have been extended as expressways (dual carriageways) (colloquially called "Yellow Autobahns"). Many of these have speed limits of usually 100–120 km/h, others have only an advisory speed limit like autobahns. Most sections of the federal highways are only single carriageway with one lane for each direction and no hard shoulder pull-out area.
Autobahn
Only federally built controlled-access highways with certain construction standards including at least two lanes per direction are called "Bundesautobahn". They have their own white-on-blue signs and numbering system. In the 1930s, when construction began on the system, the official name was "Reichsautobahn". Various other controlled-access highways exist on the federal "(Bundesstraße)," state "(Landesstraße)," district, and municipal level but are not part of the "Autobahn" network and are officially referred to as "Kraftfahrstraße" (with rare exceptions, like A 995 Munich-Giesing–Brunntal). These highways are considered "autobahnähnlich" (autobahn-like) and are sometimes colloquially called "Gelbe Autobahn" (yellow autobahn) because most of them are "Bundesstraßen" (federal highways) with yellow signs. Some controlled-access highways are classified as "Bundesautobahn" in spite of not meeting the autobahn construction standard (for example the A 62 near Pirmasens).