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):
An era is a span of time marked by character, events, changes on earth, etc. When used in science, for example geology, an era denotes a clearly defined period of time of arbitrary but well-defined length, such as for example the Mesozoic Era from 252 Maâ66 Ma, delimited by a start event and an end event.When used in social history, eras may for example denote a period of some monarch's reign.In colloquial language, eras denote longer spans of time, before and after which the practices or fashions change to a significant degree. When era is extended to a calendar system, it is known as a calendar era.hen used in social history, eras may for example denote a period of some monarch's reign. In colloquial language, eras denote longer spans of time, before and after which the practices or fashions change to a significant degree.