A gorilla is a great ape native to the forests of equatorial Africa. A guerrilla (sometimes spelled guerilla) is a member of an irregular paramilitary unit operating in occupied territory. Guerrilla is often used figuratively to describe secret or backchannel projects—for example, guerrilla marketing or guerrilla filmmaking.
Examples
Guerrilla
Osama bin Laden was the millionaire guerrilla fighter who became the world’s most notorious terrorist. [Scottish Daily Record]
FARC guerrillas have been waging war against the Colombian government for decades. [CNN]
The money was allegedly sent overseas to the PKK to help finance its decades-long guerrilla war against Turkish security forces. [Herald Sun]