Hi, I think that "he used to work" means that he worked usually in the past, is something that he did regularly during a long period of time. "He worked" means that he worked in a punctual moment in a recent past, in a specific moment, not during a period.

He used to work = He worked in the past BUT HE NO LONGER DOES. The present situation is FULLY implied. "Used to" is used to contrast a past with a present situation. He worked -> This tells us nothing about whether he still works. The two sentences are very different.

I think they are the same. We need a grammar expert here.