Both of them are expanisons for MoH:AA.
Yes, you can play them in any order as the campaigns are not linked toe ach other in any way.
Besides the expanisons being a bit more heavy on the system, all you would need is the required patches to be installed on the original game. By that I mean, you need to have MoH:AA installed and patched to be able to install and play either Breakthrough or Spearhead.
The patches are included in the expansion's disks, so you dont need to look around for them. They will initialise and be installed automatically.