They're all just repaints.
Flint is Duke with new gear and a new head. (explains the long sleeves)
Snake-Eyes is the first one with new gear and a new head.
Storm Shadow is the first one with new gear and a new head. (explains the short sleeves)
Cobra Commander, pretty obvious.
And the Officer is just a trooper with new gear and a new head. (explains the kneepads which the officer never had)

Weak.

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RIP Minouche, 1994-2009.