Hi. First, "escuela" is "school" in general: a place of learning that can be anything from a primary school (escuela primaria) to a university department (Escuela o Escuela Superior de ....), within a "Facultad". Then, "colegio" corresponds more or less to primary and intermediate school in England, and "instituto" to high school. College is more complex: if you are American, "college" is university: "universidad". If you're British a university college of residence is "colegio mayor". Lastly, there is no possible translation for "college" as it is understood at Cambridge and Oxford: these are unique institutions and as such defy the translator's skill. Note that this refers only to Spain. Other regions will have different systems.