Bullet and box cameras may look similar but are actually quite different with bullet cameras sharing more in common with dome cameras than box cameras.  A bullet camera is actually a box camera sealed inside its own housing.  They come in fixed or vari-focal varieties with and without LEDS for infrared illumination and for indoor or waterproofed for outdoor use.  Like dome cameras, bullet cameras are not serviceable and come with lenses and housings that are permanently attached.  Also like dome cameras they are usually small and are meant to be mounted discreetly.

Box cameras on the other hand are larger and have internal components and lenses that can sometimes be replaced.  They usually feature better optical performance, longer service life-span and with the right housing can be mounted in virtually any location and environment.  Box cameras are not meant to be discreet and are usually an imposing symbol of security presence at an installation to be used as a deterrent.

Pros (Bullet) Cons (Bullet)
Small Size Small camera usually performs more poorly than regular cameras
Discreet Camera cannot be replaced separately from housing
Simple installation
IR LEDs can be built in for nighttime illumination
Low cost (all in one package)
 

 

Pros (Box) Cons (Box)
Best performance type of camera High cost
Can be serviced Unattractive
Can be used in harsh environment with right housing Requires bulky housing
Longest service life Needs separate illumination for low light use
Visual deterrent