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):
To summarize: A generation in the bible is primarily the age of a man when his first male child is born; but secondarily, the age of a man at his death. The bible then rounds the exact span of years in a generation to be 40 and 100 years as the primary usage, but on occasion, 70 years. And 70 is the average of 40 and 100, which allow the three timeframes to work in numeric harmony to produce the numeric symmetry found throughout the bible.