Depending on the purpose the following types of complex systems can be identified:
- Informational systems. The systems for input, processing/analysis, and output of information. The most widespread type of system.
- Monitoring systems. The systems that track the state of some object or infrastructure, like a power plant, gas transportation network, vessel propulsory, etc.
- Control systems. The systems for handling some objects, like aircraft, vessels, cars, road traffic, etc.
- Instrumental systems. Multiple systems that combine instruments for a specific purpose, like CAD systems, publishing systems, and so on. Some of them are very close to mass-market systems and are bought by users themself.
- Utilities. Auxiliary systems for setting up other systems, calculations, measurements, etc. Compared to instrumental systems utilities can be defined as a single instrument, but they can be quite complicated.
This list is not covering all the possible options. Also most systems in real-life combine several types. But it is quite good to understand the difference between systems depending on their tasks.