Judicial review is a court's power to review the actions of the legislative and executive branches, and it usually refers to the power of the courts to consider, review and examine the constitutionality of legislation - and to overturn those laws deemed unconstitutional. It is the court's power to invalidate legislative and executive actions as being unconstitutional. It also refers to the Constitutional doctrine providing for this power.
Declaratory relief is a judge's determination (a declaratory judgment) of the rights of the parties under a contract or a statute. This is often requested of the parties to a contract to clear up a controversy, perhaps over the meaning of one of the provisions, or to clarify the intent of a law as written. The judge gives his legal interpretation of the matter.