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):
A generation is the parents, Grandparents, Grandparents. So your parents and their siblings are one generation while you and your siblings are another. The age of people has nothing to do with a generation in Genealogy, it is the relationship with others that determines the generation. So if you (at 20) and a 50 year person in the family share the same great-grandparents you are of the same generational structure.