Yes, there was a huge different in fighting in WWI and WWII. Those two wars were WORLD wars. We were standing by our allies...
Exactly like we stood by our allies in South Vietnam and Kuwait. No difference there. Care to try again? Are you under the impression that all wars accomplish the reasons for fighting? We do not speak Japanese, German, Italian, or Arabic and we remain non-communist or dominated by Islam. The fighting and die have indeed accomplished something.
Joining the service is not the same as wanting to fight and die. I was also drafted and served in Vietnam with the Army as a medic. I saw a lot of men die. None of them wanted to.