These are not exclusive concepts.  They allow a community to resist and absorb the impacts it cannot resist.  They ensure some functions will continue while allowing others to fail in planned manner that limits the impact of those failure for as long as possible (graceful degradation).  And for those functions that do experience degradation they allow either return to full operation within acceptable minimum downtimes or return with the least possible delay.  The edges of the two concepts are fuzzy and overlap, providing a continuum of capability to protect the community.