There is a big difference between a terrorist and a freedom fighter. Most times, people don't. There is a big difference between the two. At times, people just use any name for anybody that is pursuing a struggle. A terrorist is a person, group that uses fear or violence to manipulate people and cause them to behave in a certain way, for political goals. A terrorist comes with an evil ideology and uses fearful situations or things to force people to believe the same thing.
There are so many terrorist groups in the world, e.g., al-Qaeda, Boko Haram, etc. A freedom fighter, on the other hand, is someone who acts based on people's interests with a very strong determination to end any form of injustice being done to a certain group of people. For example, a freedom fighter can arise and fight with authorities in an attempt to liberate his people from oppression and slavery.