ALL ABOUT THE FEAR
Potato / potahto -- both wars have so many similarites, it's like saying which is worse, cancer of AIDS? The reasons we entered Vietnam are complex but the main reason, at least publicly, was to stop the spread of Communism to end the "Domino Theory" of one country after another being taken over by the the godless Commies. That FEAR of communism and the then evil Russians and Chinese leads me to a similarity to today's FEAR -- fear of the terrorists, i.e., Al Qaeda who hate the freedoms and open society that we enjoy. They really hate our culture of sex and drugs and rock and roll, if you get my drift. But it was the FEAR generated by the 9/11 attack that was used to get us into Iraq (Remember all the patriotic flags in plastic holders on car window? The non-existent WMD's, another FEAR ploy, played perfectly into the sale (by Bush, Cheney & Co.) of the current war.
Both wars are/were quagmires with no way out because we didn't know what we were getting into, i.e. the culture and political history, of either nation, so we don't know how to fight, who to fight, or even why we're there anymore.
One big difference is that today's army, more and more, are mercenaries, whether they are US soldiers with incentives to get them to sign on (fewer and fewer Americans want to die for nothing), or Blackwater and Blackwater-style actual mercenaries; whereas, in Nam it was largely people who were drafted, many of whom did not want to be there. It's also why the anti-war sentiment was so strong. When the privileged Jenna Bushes of the US get drafted, there are then people with power who start questioning the war.
I'll leave it at that for now, but compared to other wars, Iraq is more similar to Vietnam than different. The button I wear says, "Is it Vietnam yet?" Of course the implied answer is yes, and by extension here we are again in yet another "terrible jam, way down yonder in Vietnam," with no way out. That's because Congress and the American people were blinded by 9/11 and got behind this mess because of FEAR, not thought.