if you mean reasons, then
premanent:
-can amass as much stuf as you want since you wont move
-more time to adapt to environment and settle
-if easier to fortify (security)
nomadic:
-if attacked, easier to get away since you travel anyway
-get great at adapting quiclky to new environment
-adventure, something new, if resources run out, no problem, just move to other resources