He looks as if he were a teacher.

[keannu]

If "as if"casts doubt about the following phrase, is it a negative one like "He doesn't seem a teacher, but he seems so"? And what is the difference between ex1 and ex2?

ex1)He looks as if he were a teacher.
ex2)He seems to be a teacher.

[konungursvia]

Nowadays, you might consider them to be about the same.

But back in the days when rhetoric was something good, 1) talks about his appearance, without asserting that he is a teacher at all, whereas 2) guesses he's a teacher, without certainty, and in fact, without even saying why (looks, style, speech???)

[5jj]

This is the third thread (at least) that you have started on very similar questions. You may well get answers that confuse you if people who have not read the other htreads respond to this one.

[RobMasters]

If "as if"casts doubt about the following phrase, is it a negative one like "He doesn't seem a teacher, but he seems so"? And what is the difference between ex1 and ex2?

ex1)He looks as if he were a teacher.
ex2)He seems to be a teacher.

Some confusion here, as your first sentence is contradictory - He doesn't seem to be a teacher, but he seems so."

"He looks as if" = "he seems to be" = "he appears to be" = "he looks like he is" = "it appears as if" etc etc

Both EX1 and EX2 mean the same.