In the SunOS 4.1 system, device special files were located (by convention) in /dev. Now that the /devices directory is used for special files, /dev is used for logical device names. Usually, these are symbolic links to the real names in /devices.
Logical names can be used for backward compatibility with SunOS 4.1 applications, a short name for the real /devices name, or a way to identify a device without having to know where it is in the /devices tree. For example,/dev/fb could refer to a cgsix, cgthree, or bwtwo framebuffer, but the application does not need to know this.