IT fields can never be determined unless you refer the IT fields to a specific company. Anyone will tell you ... DB Admin, AD admin, network admin.. but in all reality, the IT department can vary SO much depending on the company that you work for. It stands for Information Technology... if that isn't a broad term then I don't know what would be...
I work for Starbucks Coffee Company. They have an IT structure full of about 600-700 people. They have IT people at the roasting plants, Districts (different countries), the support center, etc. My department is "IT Retail International" ... basically what that means is when new Starbucks stores go in in China, Puerto Rico, Japan, Thailand, etc... We dictate to them how the store should be built... network, phone lines, retail POS, etc...
There are IT people that do nothing but draw schematics all day... they aren't exactly Admins... they are just in the IT planning/strategy department.
For your homework... I know.. but it dives A LOT deeper than what you are thinking.