Type B plugs in USB 3.0 are somewhat larger; therefore, a USB 3.0 Type B plug cannot enter a USB 2.0 or earlier Type B receptacle.
Type B plugs in USB 3.0 are somewhat larger. A USB 3.0 Type B plug cannot enter a USB 2.0. This is therefore. A USB 3.0 Type B plug cannot enter earlier Type B receptacle. This is therefore.