This one is really interesting
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1 the Terran soldier clearly has something on his back, however it is NOT a jetpack. The item is iridescent purple, it could even be a Vanu Sovereignty jetpack however that seems unlikely, could it be a stealth field or some other form of gadgetry? The soldier with the strange pack also seems to have a sleeker helmet design and is also very lightly armored.
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2 the different design of the 'Heavy' suits helmet can be seen compared to the open faced 'Agile' suit, in circle
3 the extra protection can be seen around the thighs and lower legs.