Since I'm sure there may be some questions, here are the main differences:
Commander is an official EStim product; so they can test it with different firmwares, and you can phone them up if you have questions.
Estim Control/Server is not official; I can only test it against my own box (version 2.103), and I'm not very polite on the phone
Commander provides remote and local control of the 2B. So does Estim Control/Server. Both can control the other, so what are the pros and cons?
If you're just starting out, then Commander is a lot easier to get to grips with; it provides full control over the box, and has a clear interface and you can do anything with it that you can by twiddling the knobs, locally or remotely.
However, if you want to try some new things out, then Estim Control/Server has some extra features that may be useful:
• It's possible to save 'favourite' settings, and recall them later
• Those settings can be configured to fade in and out, and run for a particular time
• You can create a sequence of settings to play in order, or at random
• There's an 'adjust' option that lets you tell the box to increase by, for example, +5 over thirty seconds
For remote control, Estim Control/Server will talk to Commander 2, and vice versa, so you don't have to have the same software at each end. You can have Commander 2 talking to the 2B, and a remote copy of Estim Control/Server will be able to play back its favourites, and control sequences just as well as if it's talking to the 2B itself.
However, Estim Control/Server also does these things:
• HTTP mode, designed to allow control to be embedded in a web page
• An HTML App (Estim Remote, ESR), designed for tablet control
• Message sending between the master and slave units
• Slave mode timeout, to cut output after a specified time
• Favourites saved at the slave end can be retrieved by the web or app controllers
A consequence of all this is that you may find the interface for Estim Control/Server a bit confusing at times, especially if you don't use all the different options it offers.
Mostly, Estim Control/Server was built to allow some interesting remote fun for me and Boss; I'm happy to make it available to other people, and to offer advice on a best-effort basis, but I can't guarantee it's flawless, or that I can answer every question you have about it.
There's more information on my web site http://roughsex.org/estim together with download links.