Business Projects : "Feature Work". This is the most visible type of work.
Internal IT Projects : Release Automation, QA Automation, Developer Tooling and other internal enablers. Mostly un-tracked and invisible, but crucial to long-term success.
Updates and Changes : Generally generated from above two categories of work. Introduces delay as breadth of existing surface area increases.
Unplanned Work : Fire-fighting at all levels of the company. Ruins planned work, so root causes need to be aggressively remediated.