Flammable and inflammable both refer to materials and substances that are easily set on fire. Non-flammable is the opposite of flammable.
Mortal (formal word) / Fatal mean causing death. Lethal refers to a substance that can cause death.
Habitable usually refers to buildings and means suitable for living in. Inhabitable also refers to a place or geographical area that can be lived in, whereas uninhabitable is housing or a place that cannot be lived in.
Emigrate refers to movement from a country on a permanent basis while immigrate refers to movement into a country. Migrate is the process whereby people or animals move between countries on a temporary basis.