[LukeZ]

(Elemental) Resistance gives you an Edge point before making the Defense test against an attack of the chosen Element. You can bank this Edge point and expend it as you wish.
Toxin Resistance gives you an Edge point before making the Toxin Resistance test. You MUST expend that Edge point on an Edge Boost that affects this roll.

Is this correct? If so, why for very similar Qualities like these there is such a difference?

[Xenon]

Resistance to Toxins (and Resistance to Pathogens) is (are) more generic and cover all Toxins (and all Pathogens), but the Edge point must be spend on the defense test. Elemental Resistance is more specific and only apply to one single element, but the Edge point may be banked. Seems like a fair trade-off?