How about categorising your IT department headcount based on the software that the person has installed (and used) on their personal computer?
A technology specialist will have a compiler, debugging tools a decent editor etc. Obviously there is a pecking order. A C compiler counts whereas the VB macro compiler built into Word doesn't. Compilers for C# and Java count if they are the professional versions. They will use these tools to write and compile source code into executable code. The machine itself will be bigger and probably have the server versions of software installed. Open source software is installed from the compiled code.
The middle ground is owned by people who assemble pieces of pre-built technology and generally work with systems created by others. A Java SDK, web server (Apache or IIS), personal database (MySQL, Access etc.) may be installed. Open source software is installed from the binary distributions.
The non-technologists in the IT department will principally use project planning and resource allocation software along with Powerpoint or similar so that they can manage projects and communicate the plans and status to the business contacts. Excel will be running on an almost permanent basis. Open source software is an interesting concept that is well progressed along the Gartner hype-curve.