Until recently I assume they were synonymous 😅, Here you go to Uni immediatly after finishing HS.
It is true in my country (India), and, considering that we borrowed this system from the British, true in many other countries as well.
For example, University College London and King’s College London are part of the University of London.
The autonomy enjoyed by the colleges within a university would vary from uni to uni, and sometimes even from college to college within the same university. Generally, at least the ‘higher’ degrees are given in the name of the University.
Some universities have centrally run departments, and these are usually more prestigious than the constituent colleges. Others are purely affiliating unis and only perform administrative duties.