Difference between what he is doing and what is he doing [closed]
Solution 1:
"What he is doing" is a phrase standing in for a noun: if he is doing X, then "what he is doing" represents X, e.g. "I would like to see what he is doing" means I would like to see X.
"What is he doing" is a question, asking for the identity of X. The reversal of pronoun and verb makes the phrase interrogative.