memorial纪念物； 纪念碑， 纪念馆，纪念堂  一般与人的去逝的和事物的毁灭有关。XX纪念堂用memorial。

    monument纪念碑  往往指纪念在历史上意义的人或事或一段时期 二战纪念碑用monument。

   “Memorials are often related to death and destruction: World Trade Center MEMORIAL, Martin Luther King Jr. MEMORIAL or Titanic Wreckage MEMORIAL Bouye. A monument tends to be built to remember a significant person or event in history or a time period. The Empire State Building, for example, is a MONUMENT of the booming American economy of the period and the Arc de Triumph is a MONUMENT to military victories. Of course there is some blurrying between the definitions, but this tends to be the trend: Memorials: More somber, remembrance. Monuments: more of a mark of achievement or historic marker. (and there are some monuments, such as the Washington Monument, which -- although built after Washington's death (so a memorial) is more _symbolic_ of Washington's ideals and the constructs of American freedoms - making it a monument)”