What is the difference (both meaning and usage) between "learn about" and "learn that"?

According to my dictionary: learn about = beware of sth through information

I guess:
We should need a noun pharse after "learn about".
eg, I learn about the fact that they always read comic.

And, we should need a complete sentence after "learn that"
eg, I learn that they always read comics.

Is it true?
We learned about the latest discoveries in astronomy.

We learned that astronomers have recently made many interesting discoveries.


You are right. You have already found answers for yourself.

and I want to add a thing, learn about-->because about is a preposition, it is usually followed by noun phrases.

learn that--> that is often followed by a whole complete sentence or clause.
 CalifJim's reply was promoted to an answer.