in RP, there is little difference ( and little to really complain, really ) - but you cannot compare the harvesters to the keepers. keepers are a special faction with special ships, special weapons etc etc - and special rules. - harvesters are a normal faction - there is nothing "special" about them... they suffere and enjoy the same rules like every other player. so, harvesters are like =CR= or like the gaians.
keepers are more like phantoms or a generic terrorist ID... special rules - both for more and less freedom, but different from rules that apply to other factions.