What’s the difference between going to space and getting into orbit?

Image: Virgin Galactic. Virgin Galactic’s First Spaceflight on December 13 2018.

Humans have decided that the boundary between Earth and “outer space” happens at an altitude of 100 kilometers (62 miles). This artificial boundary is called the Kármán line — it’s basically the height that the air is too thin for traditional fixed wing aircraft to fly. So, you need something like a rocket. If a human crosses this line, they instantly become an astronaut.