It is not necessarily the end of a war, as it may constitute only a cessation of hostilities while an attempt is made to negotiate a lasting peace.
Armistices are always negotiated between the parties themselves and are thus generally seen as more binding than non-mandatory UN cease-fire resolutions in modern international law.
Under international law, an armistice is a legal agreement (often in a document) that ends fighting between the "belligerent parties" of a war or conflict.
The Convention with respect to the Laws and Customs of War on Land stated, "If [the armistice's] duration is not fixed," the parties may resume fighting (Article 36) as they choose but with proper notifications.
Most countries changed the name of the holiday after World War II to honor veterans of that and subsequent conflicts.