Dictionaries define a terrorist as someone who uses terror to achieve his end. The individual resorts to violence in order to get what he wants; he uses violence in order to make a political statement.
The word is normally used with individuals and organisations and never to a country as a whole. This explains why people talk about countries that “sponsor” terrorism.
*The terrorists threatened to kill the hostages.
A “militant”, like a terrorist, believes in something very strongly; but unlike a terrorist does not always make use of violence to achieve his ends. He will, however, not hesitate to use it if the situation demands it. He exerts a lot of pressure on others to get what he wants. Here is an example.
*The militants took shelter in an abandoned church.