What is the primary difference between ethics and morals?

Ethics is a branch of philosophy that studies morality, whereas morals are concepts of "right and wrong"

Ethics are what the EMT should do$,$ whereas morals are what the EMT will do

Morals are what the EMT should do$,$ whereas ethics are what the EMT will do

Morals define the expectations for professional occupations, whereas ethics are regulations written into state law defining what those expectations are