5 Why (or Why Why Analysis) is a tool used to identify the root cause of a problem by repeatedly asking the question 'Why'.
5W2H (Who, What, Where, When, Why, How and How much) is a structured approach to problem solving that helps in gathering basic information about the problem and/or creating a comprehensive action plan.
An application-oriented question on the topic along with responses can be seen below. The best answer was provided by Vivek Dahake on 5th Feb 2021.
Applause for all the respondents - Jayanth Sura, Vivek Dahake.