Anything indexed by search engines and accessible to the layperson is part of the surface web. As of 15th June 2023, the Indexed Web contains at least 3.61 billion pages
If the Internet is an iceberg, the web the average person accesses is just the tip.
Most of the Internet is inaccessible to the layperson. Search engines do not and cannot index all parts of the Internet. So by definition, any of the content we cannot access becomes the "deep web". The deep web can be ANYTHING, from password protected content, to private data stored on servers, web archives, anything behind a paywall, anything that requires authentication.
The "deep web" makes up MOST of the web. Private Facebook accounts, paywalled articles,
A subset of deep web. Except, this CANNOT be accessed without specialized tools.