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):
Epochs are subdivisions of geologic periods. Era-A division of geologic time of several hundred million years in duration. An era is smaller than an eon and longer than a period. Geologic Time Scale-A categorization of geological events based on successively smaller time spans: eons, eras, periods, epochs, and ages.Hadean-The earliest eon in the history of the Earth from the first accretion of planetary material until the date of the oldest known rocks.eologic Time Scale-A categorization of geological events based on successively smaller time spans: eons, eras, periods, epochs, and ages. Hadean-The earliest eon in the history of the Earth from the first accretion of planetary material until the date of the oldest known rocks.