the marines theoretically have certain warfighting specialties like ship boarding and amphibious assault but from a general ground war perspective they're not as capable as army units. mostly for logistical reasons

in general I doubt there's any significant difference in quality of troops between the branches. which one you pick depends on what you want to do, e.g. when I was enlisting, if I had gone into the marines they would've shoved me in some gay computer nerd job and I wanted to be infantry. the army guaranteed me infantry, so I chose the army