I think "resistance" is generic, but for the purposes of the timeline they are specifically the Resistance of Eden Prime - the first Cradle World in the Reclamation by the UCM. The Ferals are various Warlords that refuse to cooperate with the UCM, and so are limited in what they have access to. Both Resistance proper and Ferals can use military and improvised equipment but I believe at different ratios, and the Resistance proper has access to some UCM gear, I believe.