Python

Docstrings are important and their role is different than comments. They give an overview how the function works, explain parameters and sometimes give examples how to use them. You can generate documentation using sphinx from Docstrings, and as others said IDEs use docstrings to show you information about function you're using.

Comments are just text that gets ignored by interpreter. You can add explanation to code if it's not self explanatory, but they're not useful outside of the immediate area being commented on.

Other languages also have documentation options that is separate from comments, e.g. JavaDoc. The syntax is usually similar to coment, but slightly different to differentiate it from comments (extra * in multiline comment).