Here are some of the differences at "top" schools:

• Many professors are luminaries in their field. You'll be taking a class from the person who wrote the textbook everyone uses. Your next class is taught by the person who literally invented/discovered the technique you're learning that week.
• The students are more highly motivated, on average. You're surrounded by "people who wanted to go to a top school", rather than "people who wanted to go to college".
• For better or for worse, you're surrounded by wealth. Some of your classmates will have wealthy parents and connections.
• The schools have a lot more money for fancier equipment and labs.
• Companies love the prestige of hiring from top schools. You'll be recruited heavily.

It doesn't necessarily mean you'll actually learn more. Really that's mostly up to you. I do think there's a difference in difficulty and expectations for courses, but it may be that's more due to the average caliber of students being higher rather than the school actually teaching more.

Also, not all top schools prioritize teaching quality. Many small liberal arts colleges have 100% of courses taught by full professors who care about teaching, while many top universities don't prioritize teaching, especially lower-level classes, and many undergraduate classes are taught by grad students who don't have any teaching experience.

How much you learn is mostly up to you. You can learn just as much and have just as many opportunities at an average school, but you might have to work harder and seek them out. At a top school, it's harder to get in, but once you get in you'll have more opportunities.