The two are near synonyms. Prophecy is more than just preaching, but it is mostly preaching. But routinely they were confronting people with the Holy One of Israel and the sin of the people, day in and day out. We like teachers much more. They explain things.
Prophets speak of eternal realities such as hell.
They cut like a knife and pierce through with holy fear. The smarmy, vague, soothsaying now currently wearing the name is not even close. Consider, for example, the style of Christ in the directly dictated letters of Revelation 2-3. When I was 16, an armed guard at my high school pulled me aside and told me that he could read palms. All this was true, and I was mesmerized.