"Etwas beenden" is transitive ("to end s.th."), "enden" is intransitive ("to end"). Examples: Der Weg endet. Er beendet sein Studium. Quite a few X/be-X verb pairs are used in a similar way. I'd recommend to always learn the complete expressions, with pronouns and cases, and not just the verbs. You can find them for example in the Pons dictionary (http://de.pons.com/).