Making multiple pages different with the same template Lets say I have four different pages I set up on a channel to have four different directories. ie ... hello/1, hello/2, hello/3, hello/4. But they are all using the same template.

What could an engineer adjust in craft to be different between the four pages vs. not be able to adjust if they can't touch the html template or CSS?
You could try creating a different entry type for your "hello" section.

For example, I am building a site for a restaurant. The "food" section is a structure. Each entree is the same template, each "category" uses the same section, but a different entry type. That way the admin only has to click "new entry", then choose either "entree" or "category" as the entry type. 

Each category gives me the titles, "sandwiches" "burgers" etc, then my entree type is the actual food item.

Depending on what they pick, input fields will be different, however the markup on the page remains the same.