Stagers
Stagers setup a network connection between the attacker and victim and are designed to be small and reliable. It is difficult to always do both of these well so the result is multiple similar stagers. Metasploit will use the best one when it can and fall back to a less-preferred one when necessary.
Windows NX vs NO-NX Stagers
Reliability issue for NX CPUs and DEP
NX stagers are bigger (VirtualAlloc)
Default is now NX + Win7 compatible
Stages
Stages are payload components that are downloaded by Stagers modules. The various payload stages provide advanced features with no size limits such as Meterpreter, VNC Injection, and the iPhone 'ipwn' Shell.
Payload stages automatically use 'middle stagers'
A single recv() fails with large payloads
The stager receives the middle stager
The middle stager then performs a full download
Also better for RWX
