This region provides high-level medical services.
He attends the local prefectural high school.
高 is a bound prefix that only occurs inside compounds like 高温, whereas 高い is the independent adjective meaning 'high' or 'expensive' that can stand alone in a sentence.
Derived from the kanji 高, meaning 'high' or 'tall', used as a bound morpheme in Sino-Japanese compounds.
expensive; costly; high-priced; valuable
tall tree
elevation; height above sea level
high-performance; high-efficiency
high mountain; alpine mountain
high-rise; multistory; tall (building) · high-altitude; upper (atmosphere, air current)
high temperature
sharp rise; soaring; surge
plateau; tableland; highland
high voltage; high pressure
high image quality; high resolution
supreme; sublime; highest
high official; senior government official
elevation; uplift; upsurge
middle and high school · medium and high level
high school graduate; having a high school diploma
noble; exalted; high-born · noble (character); refined; dignified · precious; valuable; expensive
high place; height; altitude · broad perspective; big-picture view
High Court; high court of appeal
elevated; overhead
high fever · intense heat; high temperature