Because I am hopelessly addicted to this trailer, I felt compelled to scour this scene from the new The Force Awakens trailer to see how many different “First Order” troopers can be picked out. Click on through for an image labeling each type. Mild spoiler warnings apply.

Click image to enlarge

As you can see there are at least 9 different types of troopers in this one frame alone:

Stormtrooper (standard)
Stormtrooper Commander (Orange Pauldron)
Chrome Stormtrooper (Captain Phasma)
Flametrooper
Snowtrooper
TIE Pilot
Shield Stormtrooper
Heavy Stormtrooper (has additional webbing and pouches on chest)
Navy Troopers/Gunners (Black)

If you get a spare minute or two, scrub through the few frames and see if you can spot any more.