I had the impression they were essentially synonyms, and this was borne out by two university courses in philosophy which I took. That said, googling "morals vs ethics" turns up quite an interesting mess. A variety of contrasting perspectives showed up:
- Ethics come from an external source, whereas morals come from within
- Ethics are rational and structured, whereas morals are more emotional
- Ethics is a philosophy or code of behavior, whereas morals refers to beliefs and conduct
- Ethics and morals are used interchangeably
It seems nobody agrees on what the words mean. Which, on reflection, tracks. For me, the idea of an HR training session on ethics is laughable, but for someone who thinks of the word differently it could certainly make sense.
Personally I tend to feel like your second bullet - ethics are based on rules whereas morals are based on emotions.
That said, picture someone killing a kitten and someone else killing a cockroach. One could prevaricate all day with highbrow reasons for why the first is monstrous and the second is perfectly moral -- but honestly, for most people, I suspect it comes down to the fact that kittens are cute and cockroaches aren't.