Guerrilla comes from the Spanish for little war as distinct from the large scale operations of the last two world wars. It was used by Lawrence against the Turks to good effect. It is an effective approach being used in Afghanistan and Iraq against American invaders at this minute. Che Guevara emphasized rural operations. Carlos Marighella wrote about taking war into the towns. There are practical differences.
Che Guevara
Guevara was a mass murderer and communist subversive. What we are
told about the man is very selective; facts with a liberal covering of lies.
IRA
Was active around the time of the First World War, helping Ireland become two separate states. It became active again in the 1970s. It was then a very effective Marxist outfit.
Carlos Marighella
QUOTE
Carlos Marighella (5 December 1911 – 4 November 1969), was a Brazilian Marxist revolutionary and writer.Marighella's most famous contribution to guerrilla literature was the Minimanual of the Urban Guerrilla, consisting of advice on how to disrupt and overthrow an authoritarian regime aiming a revolution. He also wrote For the Liberation of Brazil. The theories laid out in both books have greatly influenced contemporary ideological activism. Unlike Che Guevara, who proposed guerrilla activity in the countryside, Marighela's theories on urban guerrilla warfare envisaged cities as the source of rebellion.
UNQUOTE
Another communist, another trouble maker but quite possibly justified by corrupt government. He is spot regarding ammunition. It is far to easy to waste. He will have seen too many trigger happy twerps blazing away without result.
PS His Minimanual is at http://www.marxists.org/archive/marighella-carlos/1969/06/minimanual-urban-guerrilla/index.htm