In any story, you have to introduce your readers to two things: the characters, and the world.
Visual media like movies can do this fairly easily. The opening minutes of Star Wars are classic. Even without the brief screen-crawl of A New Hope, we see the tiny ship fleeing the Star Destroyer, the terrified Alderaanian crew, the invading Stormtroopers, the capture of Princess Leia and the droids’ escape. Established: SF setting, desperate rebellion, a princess in distress who’s been fighting a shadow war by espionage, the terrifying Darth Vader, and our plucky metal duo. Extremely effective.
…Very hard to pull off in a verbal medium.
Granted, some books make a good stab at it. “The building was on fire, and it wasn’t my fault,” gives you solid clues as to the kind of person Harry Dresden is (walking disaster zone) and the next few pages of fighting off flying monkey demons to rescue a litter of temple dog puppies sets up “this is a version of our world with magic and a Masquerade to hide it”. Plus, puppies. Any fluff-rescuer can’t be all bad.
Part of the difference is in what primary sense is involved to convey the information about your world and characters. The visual medium is faster. You see, you analyze, you react. You can get in a lot of information in a few seconds. Which is how we big-brained primates are primed to react: take in the scene, quickly pick out allies, enemies, threats, and resources, and make a decision before a threat or enemy gets too close. (It also means you can miss things, and rewatching can be surprisingly rewarding.)
The verbal medium is slower. Yes, a regular book is visual in that you see the words, but most readers build the meaning verbally, word by word. Good writers make “voices in your head” by word choice, turns of phrase, descriptions of movement. The details come more slowly, but can be studied more finely. Your brain is shaped for that, too; picking up sensory data from a distance with hearing means you usually get more time to digest it.
This, BTW, is how blind people who echolocate navigate. They “paint a sound picture” of their surroundings by echoes, bit by bit. It takes longer than sight, but it can be more effective. A sighted person in a hurry might miss an open manhole cover. Someone echolocating will hear the void.
Next time: How does introducing your characters to your reader differ from introducing your world?