The main difference is the ability to be published.
To break into TV, you need to live somewhere that produces a lot of TV shows (in the United States, you'd move to Los Angeles and try to hang out with others in "the industry"). I'm not sure how else you break in, but it's not easy.
You can self-publish 100 novels with the same ease (and money) it takes to make one 30 minute TV pilot. More eyeballs too. Perhaps there are paths to film/TV writing available to you (by networking or luck) that I don't know about. The reality for most people is that you're a lot more likely to get published with prose, and even that's not easy to do.
But you asked about "forms and styles I can use in my writing that are not possible to do with film and TV."
Forms & Styles
My current project was in my head as a movie for 10 years. I imagined scenes and camera angles and all the rest. I don't have the skillset to write a screenplay (the technical stuff isn't hard to learn, I just don't know it yet) but I could have gotten it down easily enough and reformatted it later.
When I decided to change course and write it as a novel, it was an interesting transition. At first I decided to create it as a heavily illustrated book. Not a graphic novel, but something leaning in that direction. I don't draw but I did choose an artist (who I still think would be perfect) who has agreed to work on it when I'm ready.
My first few chapters were good enough but relied heavily on the illustrations for descriptions (I have those illustrations in my head and described them briefly). For example, Chapter One (after a prologue) happens with an extended family around a dinner table. My prose only barely showed the reader what the characters looked like, how the table was set, what the room looked like, etc. Some of that stuff was window dressing (but a well-dressed window is a joy to look at) but other details are important to the story.
As I continued to write, I stopped relying on the pictures and started narrating.
Description: A screenplay shows you the characters and the setting, sometimes in glorious detail, but it's a barrage. With prose, you can set the scene sparsely or lavishly. The reader can imagine to cover any gaps.
You also can direct the reader's eye. Of course you can do this in a screenplay too. It's called a closeup. Prose gives you more subtlety. You lay out the important parts without necessarily pointing a big sign at them screaming "foreshadowing!"
Character thoughts: There are many forms of narration in a novel. Some allow you to get inside anyone's head, some only one person's head or a small handful. Some don't do it at all.
When I started writing this novel, I had every intention of limiting my narration to what could be filmed. I only included the slightest of thoughts, and then just things that a good actor could convey without words. As I went further, I changed that. And the novel got stronger.
It's not necessary to include thoughts, but most novels do, at least for the main character (or a narrator who is involved in the action). You can easily overdo it but, done right, it brings a depth to the characterization that is hard (and sometimes impossible) to capture in film.
When people talk about the difference between reading the book and seeing the movie and how the book is (usually) better, it's because the book gives you more than a movie can. Length is a huge factor, but also how the characters feel.
Length: Novels can have sequels and TV shows can go on for decades (some soap operas have). But the reality is that you can pack in a lot more information in prose than will fit in a script. When novels get adapted to movies, large portions of plot get cut, subplots are often removed, and some characters are merged with others or just gone.
Nuance: You lose character complexity and other nuances that a novel can give you. If you're transitioning to thinking about your work as filmable to just printed, imagine the world this opens up for fleshing out secondary characters, showing more stops on a journey, or simply taking your time with a story.
Time-depiction: Film uses actors and they are the age that they are. You can use makeup to age an adult and you can go backwards some, but often you need new actors to use in flashbacks or subplots about characters at other ages. Some TV shows do hire actors to show the characters as children or young adults, for example, but they tend to merge ages to limit this.
The TV show Any Day Now has parallel storylines with an adult cast and with them all as children. Orange Is the New Black mostly sets stories in the present day but shows individual characters before they got to prison. Some use the same actors and others use younger adult actors, teens, or small children.
Child actors also age, so if there's a delay in filming, you might end up with a much taller actor (suddenly with breasts or facial hair) because you waited 9 extra months for funding, but the time jump is supposed to be a single summer. It's even worse if you have to skip a season (as many shows do these days) and have the perfect young actors who are going to age out.
Time Jumps: In prose you can skip ahead 5 years without even blinking. The show Jane the Virgin did this between 2 seasons, but they had to recast the children. The adults didn't age visibly because...Hollywood. Pretty Little Liars also jumped ahead, but in that case it was a relief because we no longer had actors in their 20's playing girls in high school. Now the same actors were playing characters closer to their real ages.
In prose you can also go back and forth through multiple timelines with ease. If you want an entire chapter set 20 years ago, no problem.
Settings: You don't have to consider how expensive changing sets is or how you don't have the budget to film on location. Just write it.
Background information: Does the reader need some information to make sense of the story? Your narrator can just tell the reader. You don't want to infodump, but sometimes it's just easier to write a line or two of background. In film, a character has to know the information and tell another character (which might not be what you want for the plot) or somehow tell the audience (reading a diary out loud, inventing a throwaway character like a therapist, etc). For something super important, that's okay. But sometimes you just want a line or two every few pages.
I've left out a few, but hopefully this is enough to get you started.