TOPIC: Fifty Years?

Would you mind telling me whether the following four phrses are the same meaning?
1)fifty years away
2)in the next fifty years
3)in the coming fifty years
4)in the first fifty years
Sincere thanks, from the bottom of my heart.

#1,#2,#3 are all about the same, but #4 is different.
" in the first fifty years" would have some point of time reference that the other three do no have. For example,
"In the first fifty years of Shanghai's existence, it was a small fishing village. the next fifty years saw a big influx of people from other parts of China."