The difference between using “to discuss” or “discuss about” is that “discuss about” is an incorrect phrase. You wouldn’t use “discuss about” but you would say “discussion about.” In this latter instance, “discussion” is a noun. “Discuss” is a transitive verb which means it requires special attention.
“Discuss” is tricky specifically because it’s a transitive verb. This means it will always require an object after the word appears and not a preposition, such as “about.” However, there are other synonyms for “discuss” that would incorporate “about.”
“To Discuss” as a Transitive Verb
Transitive verbs have the strict rule of requiring a direct object following immediately after its appearance in a sentence. Transitive verbs are often indicative or suggestive of an act of giving that requires an object of reception. “To discuss” is one such verb.
We discussed the notes from Prof. Lehman’s lecture.
I discuss only those subjects that interest me most.
She discusses deep and thought-provoking subjects.
Using “About” with “Discuss”
“Discuss” as a word and a verb are direct and to the point. It requires a definition for clarity of expression and understanding. If you use “about” in the sentence, this will muddy meaning and intention. Study the examples below:
We discussed about the notes from Prof. Lehman’s lecture.
I discussed about only those subjects that interest me most.
She discusses about deep and thought-provoking subjects.
While these are technically correct in their construction, they aren’t proper English grammar. First, it takes much longer to get to the point of the idea. Second, it tends to drag the sentence on and shifts the focus away from the main idea.
Synonyms for “Discuss” that Use “About”
However, there are plenty of other verbs that you can use in place of “discuss” when you need to use, “about.” These include “talk,” “speak” or “tell.” While these could also use a direct object, they don’t always need one.
We talked about the notes from Prof. Lehman’s lecture.
I speak about only those subjects that interest me most.
She tells about deep and thought-provoking subjects.
The easiest way to remember you don’t use “about” with “discuss” is that it’s the only synonym of the group that DOES NOT need to have it. This is because “discuss” requires a direct object to complete the idea. The others can too, but it is entirely optional.