React: Playing with Functions and Classes

Have just found this. They certainly do the same, this is the result

Browser results

But the code can be quite different.
Using functions:

Using a function in React

See that we are declaring the function receives props, though at first sight one, we don't know the nature of them.

Using classes:

Using a class in React

For the class, we are not declaring it receives anything. Do I have to suppose this? May be there's a misunderstanding, and there is a proper way to declare props.