The difference between 'armistice' and 'ceasefire' please.

Hi,
I'd be much thankful if you could help me get the difference.

They are synonyms. "Cease fire" is usually used today, perhaps because the word "armistice" became associated with the end of World War I on November 11, and the subsequent "Armistice Day" to remember. (This holiday is now called "Veterans Day.")

I would consider a ceasefire to be potentially more temporary. Warring factions quite frequently call a ceasefire but it can last from hours to weeks. An armistice is usually more "official", with the leaders of the warring factions signing papers declaring a war to be over. I would say that an armistice might come after several ceasefires.