"Guntai" is "The Defence Force". And, "Guntai (The Defence Force)" contains "Rikugun (The Army)", "Kaigun (The Navy)" and "Kuugun (The Air Force)". "Jieitai" is "the Self-Defence Force". That is, "Guntai" can start the war with other countries, but not "Jieitai". "Jieitai" will fight only when "Guntai" from other countries attack the country. Make sense?

Nice to meet you, @Ádám. I explain about this questions in my awkward English skill. 1. "jieatai" is "The self-defense forces" in English. >> This word mean "The army which isn't allowed to fight only for self-defense". 2. "guntai" is "The forces" in English >> This is a general term of the navy, the army, and the air force. 3. "rikugun" is "The army" >> This is an army to which a foot soldier and a tank belong.