使用正则表达式（或其他python模块）来比较文本/字符？

Let's say that my program receives an input such as a string of characters that has any type of character. For example, 'Bob's Bagel Shop'. Then it gets another string that says 'Fred's Bagel Store'. How can I use regular expressions or some other module in python to compare these and have my program tell me if at least 5 (or any number I want) of the characters are the same Let's say that my program receives an input suc