The specification of IP cameras is quite complicated as most of the features are technical.  We attempt to compare features of the ACTI brand of industrial grade IP cameras here rather than explaining technical features. 

Megapixel refers to 1280 x 1024 dot resolutions of the image quality, otherwise 64x480
POE stands for Power over Ethernet
D&N stands for Day & Night vision of the camera
IR stands for Infra Red vision of the camera
VF stands for Variable Focus (normally from 3.3-12mm, otherwise fixed at 4.2mm)
OD stands for out door with Protection against Ingress of Moisture and Dust IP66
VP stnads for vandal proofing with hardened glass housing
PTZ stands for panning, tilting and zooming

Model     IP   Mega POE D&N  IR    VF   OD  VP    Shape
CA7411    v      v      v     v     v     v     v     v      Dome
CA1231    v      v      v     v     v     v     v             Bullet
CA3511    v      v      v     v     v     v                   Dome
CA1511    v      v      v     v     v     v                   Bullet
CA3411    v      v      v     v                                Dome
CA3401    v      v      v                                       Dome
CA4201    v      v      v                                      Cube
CA4200    v      v                                              Cube
CA4000    v                                                     Cube
CA8201    v      v      v                                      PTZ
CA8211    v      v      v     v     v                         PTZ