How does training for a 5k differ from marathon?

Been running for about a year now, I don’t really have the time to get a solid marathon training block due to work and tbh it doesn’t really interest me that much either. I much prefer the 5 or 10 for racing and I’m chasing sub 20 atm. But it’s become clear to me that a lot of the running advice on the internet is created for marathon training. How does training for middle distances change training? Do long runs cap out much shorter than if training for long races?