Monuments are structures made to specifically commemorate people or events. They are an aid to the recollection of times past, maps to the legacy of culture, objects of meaning.
Monuments can also be examples of architecture important to history.
A memorial is an object that signifies the memory of something, usually a person who has died, or an event in history. Popular memorials include parks, landmarks, and works of art.
Memorials most people can find connection to are gravestone markers or the memorial crosses seen row on serried row in military cemeteries, or plaques commemorating people who have died in our long series of human wars and conflicts.
Monuments and memorials can easily fall out of fashion, and out of popular memory.
Or they can fall behind the wrong geographic or national boundaries or be obliterated altogether.
They are subject to the political as well as the emotional need felt by most of us to preserve our portion of the times and record them.
How can you tell the difference between a monument and a memorial? Here's one answer, as expressed by philosopher Arthur Danto:
“We erect monuments so that we shall always remember, and build memorials so that we shall never forget.”
~ Clare Sharpe, Museum staff member