Difference between a verb and an adjective that looks like a a verb

How do you tell the difference between a verb and an adjective that looks like a verb?

For example, "he is working." To the best of my understanding, "working" could function as either a verb or an adjective depending on the meaning of the sentence. How can you tell which it is?

Solution 1:

Working as an adjective modifies a noun, as a verb it does not.

working (verb) - He is working on a new project.

working (noun) - Working is essential for our cognitive function.

working (adjective) - He's a working man who has never been on welfare.

Examples from the web

• "...with all men working, there would be so much food that each man would have to work not more than two hours a day."

• "Besides this, she was working in one of the dark holes, by electric light."

• "Childcare for working mothers."

• "There is a good working relationship between the departments."