http://halo.xbox.com/halo4#!images/screenshots/ce74650a-bfc6-4126-a02d-d7db778eff25
In this screenshot (Halo 4 Campaign Screenshot 1) I see Chief, a marine on the right side. and I see a a guy with a blue helmet. Now Im wondering if its an ODST or a Spartan or other. I hope its a spartan because I really wanna run into Spartans of any kind during the Campaign. 
Keep in mind, Spartan IV’s are mostly inducted servicemen, so it very well could be both ODST and Spartan.
They’re Spartan-IVs! 
Those are ODSTs and a regular marine. We will likely encounter S-IVs during the campaign, but the characters seen in the screenshot in question are not not S-IVs.
They are Spartans-IV for sure… look at the armor, and that helmet looks cool!
No way those are ODSTs. Look at the armoring, especially around the top of the shoulders where the thrusters are. Anyone who thinks they are ODSTs needs to get their eyes checked.
They’re Spartans. ODST’s would be less heavily armored, and their armor is of a completely different design; darker, and with more of a composite look than a metal one
> No way those are ODSTs. Look at the armoring, especially around the top of the shoulders where the thrusters are. Anyone who thinks they are ODSTs needs to get their eyes checked.
Those are ODSTs. Look at the helmet and the armor. It looks nothing like any of the armor sets we’ve seen. The characters are clear not wearing Mjolnir, and the armor has no characteristics of Mjolnir.