When you write, you're talking on paper or screen, which provides pause and the chance to think about something more deeply. When you talk, you're writing with your mouth. Both the same, yet different tools.

Written and spoken language can exist separately in the brain, a new study from Johns Hopkins shows.

"Actually, seeing people say one thing and -- at the same time -- write another is startling and surprising," Johns Hopkins cognitive science professor Brenda Rapp told the website Futurity. "We don’t expect that we would produce different words in speech and writing. It’s as though there were two quasi-independent language systems in the brain."

Futurity, a non-profit website that shares university research, explains, "While writing evolved from speaking, the two brain systems are now so independent that someone who can’t speak a grammatically correct sentence aloud may be able to write it flawlessly."

The study, titled "Modality and Morphology: What We Write May Not Be What We Say," was published in the journal Psychological Science.

There is a region of your brain that is going to be encoding language, but there seem to be different neural pathways for accessing that general region (visual, verbal, aural).
So, with these extraordinary examples, our conclusion was that it is not at all unreasonable to think that a person could be better at written language than verbal language, and at expressing their comprehension of language better through writing as opposed to speaking. And indeed, this point has been highlighted in non-neuroscience based studies of the most effective ways to teach children: whether teachers should talk to the students or should draw on the board.

https://neuroscience.stanford.edu/news/ask-neuroscientist-spoken-versus-written-language

There are four primary learning styles: visual, auditory, read-write, and kinesthetic. People learn using a variety of these methods, but one method is usually predominant.

Scientists and psychologists have developed a number of different models to understand the different ways that people learn best. One popular theory, the VARK model, identifies four primary types of learners: visual, auditory, reading/writing, and kinesthetic. Each learning type responds best to a different method of teaching. Auditory learners will remember information best after reciting it back to the presenter, while kinesthetic learners will jump at the chance to participate in a hands-on activity.