Apocalypse- The complete abandonment or destruction of the world or everything on it.
Post apocalypse- The aftermath of an apocalyptic event (an event of mass destruction).

Examples:
Mad Max

World War Z
28 days later
legion
Terminator 2
       








Develop your own idea for an apocalypse film
Story:
Sgt Cameron Lance is on the frontline serving his 3rd tour, and his final one as his wife annabelle lance is expecting a child soon. After 3 months in iraq his best friend and brother in law Bellamy Staton was murderd in front of Camerons eyes. Over come by anger and grief he deserts the army to hunt down the man who killed his brother in arms. He soon discovers the man was a great war lords son. In his pursuit of khal durr and if needs be his father known as skull keeper he undercovers  a building full of nuclear weapons. Knowing that his vengeance is much less important than the lives of everyone in the world including his wife he attempts to remove the uranium to prevent a world catastrophe but as he does this he is spotted by khal he becomes distracted and attempts to kill him but in doing so he accidentally throughs khal into a control board that sets off the nuclear weapons one for each major city or town. He falls to his knees in despair as khal stands and attempts to kill cameron a massive explosion goes off in the base creating mass damage and causing khals death. Cameron wakes up miles from the building he can barely move and can't remember anything about his past other than the name annabelle. After weeks of barely surviving he discovers that he may be the last man alive but he's not alone. The other things he is joined by are mearly shells of men but if anything they are creatures. As he remembers nothing he has no memory of bellamy or his murderers father who is still alive but severely de formed and becomes mutated and is now in control of an army of the dead. The skull keepers control cannot be kept on his own but he has help from his second in command bellamy.