As per IAS 28 which should come into force from annual reporting periods beginning on or after 1 January 2013, these two terms have two different meanings:
Joint arrangement is an arrangement of which two or more parties have joint control
A joint venture is a joint arrangement whereby the parties that have joint control of the arrangement have rights to the *** assets of the arrangement
That means a joint venture is a type of joint arrangement
Joint arrangements are governed by IFRS 11