So the answer is found here: http://minecraft.gamepedia.com/Seed_(level_generation)

Which even though it's already linked on this page no one seems to have read it all.

To summarize:

If you use a word or phrase then String.hashCode() is called and it limits your maximum amount of seeds to 2^32 because of it's implementation.

If you enter your own number or let the system determine the seed then your seed limit is 2^64 seeds.

HOWEVER:

If it's a multiplayer world they implement the nextLong() java function and the limitations of that are 2^48 possible seed options.

So the answer is found here: https://minecraft.wiki/w/Seed_(level_generation)

Which even though it's already linked on this page no one seems to have read it all.

To summarize:

If you use a word or phrase then String.hashCode() is called and it limits your maximum amount of seeds to 2^32 because of it's implementation.

If you enter your own number or let the system determine the seed then your seed limit is 2^64 seeds.

HOWEVER:

If it's a multiplayer world they implement the nextLong() java function and the limitations of that are 2^48 possible seed options.

So the answer is found here: http://minecraft.gamepedia.com/Seed_(level_generation)

Which even though it's already linked on this page no one seems to have read it all.

To summarize:

If you use a word or phrase then Java.hashCode() is called and it limits your maximum amount of seeds to 2^32 because of it's implementation.

If you enter your own number or let the system determine the seed then your seed limit is 2^64 seeds.

HOWEVER:

If it's a multiplayer world they implement the nextLong() java function and the limitations of that are 2^48 possible seed options.

So the answer is found here: http://minecraft.gamepedia.com/Seed_(level_generation)

Which even though it's already linked on this page no one seems to have read it all.

To summarize:

If you use a word or phrase then String.hashCode() is called and it limits your maximum amount of seeds to 2^32 because of it's implementation.

If you enter your own number or let the system determine the seed then your seed limit is 2^64 seeds.

HOWEVER:

If it's a multiplayer world they implement the nextLong() java function and the limitations of that are 2^48 possible seed options.