Why some people enlist in the Marines vs. why people enlist in the army as a airborne infantrymen and such?

So before reading anymore i want to let everybody know that this is not another who's better marines or army. This is simply me wondering what leads some people to enlist as infantry in the marine corp vs. why some people enlist in the army to be like a airborne infantrymen or whatever. I know I want to go into some kind of combat MOS. And i see alot of marines that are deploying to afghanistan because of the organazation i vollunteer with. But i just want to know what drives people to want to join the marines. I guess in my mind an army airborne infantrymen would be more supperior over the infantry marine becuase of just the training that each soldier goes through. Now this is just a general discussion involving just the average infantry marine and the average army airborne infantrymen. To me enlisting and getting to go to airborne school and such sounds awesome deffinately with the army becuase from what i understand the army ranks up rather quick it says in 3 years on average a soldier in a combat MOS like 11b is an e4. Now I am asking this question becuase i have been racking my brain trying to figure out the one thing that all marine infantry enlistees have in common and why they chose the marines over another service such as the army. Also If you think about it the marines dont really have a spec ops forces and there isnt alot of extra things like airborne, or the army rangers, or special forces like that in the marines. So can someone answers my question