Spoken word and written text have a key, or primary, difference.
What is written text? Well, it's exactly that! It's written. You read it, right? You may not catch nearly as much of the characters voice within the text because it's only text. Does that make sense? I hope it does. Let's move on.
What is spoken word? Well, it's just that! Words from a person's mouth. We can hear it, feel the speaker's emotions, and sense personality within their tone, unlike text.
In certain cases, text can appeal enough to the senses to create the so called "illusion" or "feel" or whatever you'd like to call it, of the character(s) personality, feelings, actions, and more.
This is my answer and my take on your question. I hope this helps! ^-^