In the UK, we have mandatory education from 5-16, which is "primary" and "high" school (you go into high school at 11). 16-18, we have "college", which is our first round of further education. It's optional. You usually get "A-Levels" there, but they also offer technical & vocational qualifications. University is after that, and offers both undergrad (such as bachelors degrees) and post-grad (such as masters or phd) studies & research.
Americans might be interested to know that bachelors degrees take three years to complete here, and that's partly because specialisation begins at the college level, and because study in university is usually completely specialised (no minor).
Nobody ever conflates "college" and "university" here. We also never use "school" to refer to college or university. School is exclusively used for the primary/high school. I'm gathering from this thread that "university" technically means something different in the US...