systematic adj. following a devised plan in a methodological way.
systemic adj. relating to a complex but cohesive system. This was originally a term specific to the body (ex. systemic infection) but is now used to describe other complex systems as well (ex. systemic racism in governments).
Word in the Wild: The only way your company can address this systemic breakdown in communication between departments is by following my innovative and systematic approach to employee seating arrangements.
Still vexed? You can find a complete list of the Word Blog’s lexical vexations here.