I think that the basic difference is that “like” introduces a comparison whereas “as” expresses identity. ) To make , it is difficult to do.

He works like to make a car.

How Mr. Miller works is different with how he works as a mechanic.

He works as a mechanic.

What is a mechanic job?

The English traditional general grammar can employ “as” as a conjunction but “like” can’t hold it; all they are using is an alternative.

I made this: “As I said earlier”. “Not like I said” earlier. I’m afraid this is a rule I don’t like that others will.