Difference Between Custom 404 Error and Soft 404?

[tennywilson]

404 Error:

The HTTP 404 Not Found Error means that the webpage you were trying to reach could not be found on the server. It is a Client-side Error which means that either the page has been removed or moved and the URL was not changed accordingly, or that you typed in the URL incorrectly.


Soft 404 :

Soft 404 errors is when your site give 404 error without 404 http status code.
It can happened on old CMS systems(or unfriendly ones) that show thin\similar pages or show the homepage instead of 404 errors.