According to Mayo Clinic, Down syndrome causes a distinct facial appearance, intellectual disability, developmental delays, and may be associated with thyroid or heart disease in a person. So calling people with this syndrome 'Mongoloid' is extremely vulgar and disrespectful to ethnic Mongolians. Likewise, how will the population react if Down Syndrome was associated with 'European' looks? If you use this term, you are automatically a xenophobic, in my opinion.
If any difference is noteworthy, it would probably be that an age is usually between two times, e.g. 1290-1450AD, whereas an era is less set - but that isn't a rule, its just a matter of usage. Synonyms would be epoch, or eon. Source(s):
What is the difference between War and Battle? â¢ A battle is a small part in a war and a war is made up of several battles. â¢ Battle is actual fighting that takes place while war is more of strategy and planning. â¢ Battle is the real action in a war. â¢ The outcome of a battle does not decide the winner of a war. â¢ Battles are of smaller duration than wars.