Simple as it is, a wiki has content model. What you type in the Title field is the…title, and what you type in the Body field is the…body. The title isn’t the body and the body isn’t the title, and we know this because there’s a declared model behind it. Simple as it is, those two things are distinct, named attributes.
We’ll call this the built-in model. This is the model the CMS uses internally, and enforces at some level.
It’s common for most systems to require every object to have a Name or Title attribute. Often, every content type gets that by default. Many systems will also have another text field for Body or Content or Text. While it stores characters just like the Title it’s generally a larger field, accommodating more text, such as a raw textarea or a rich text editor.