The Car Cigarette Lighter was originally atiny stove-topthat would light up red-hot after a few minutes of high current and light up your nasty habit. It doubled as a 12V DC Power Outlet. Later in some new cars the Cigarette Lighter doesn't light ciggies, but is just an offic...
The other, probably rated at about 20-30 amps, protects components not wired through the ignition — horns , interior lights and the cigarette lighter. Where a single fuse protects a number of circuits and keeps blowing, each circuit must be checked individually to discover which one is faulty...