Cyber terrorists seek to use hacking to cause large-scale destruction and harm. In some ways, they can be thought of as extremist hacktivists, who seek to use intimidation and destruction to further their cause.
While cyber terrorists are unlikely to be working alone, they may lack easy access to resources. That being said, world governments have a history of covertly funding terrorist groups so there’s no reason to suspect that the same couldn’t be true for cyber terrorists.
Cyber terrorists are likely to target systems that would cause significant damage or loss of life if compromised: Digital or physical infrastructure such as backbone routers, power plants, water treatment plants, hospitals, etc.