What is the Aqueduct near Lake, River?

[Mahler]

What is the difference between the Aqueduct and the Aqueduct near a lake (river)? I play 3.1.5, civ2civ3, hard AI. In classic, there is no need in Aqueduct near rivers and lakes. I found good, there are new units like elephants, crusaders.

[cazfi]

See Help -> City Improvements -> Aqueduct / Aqueduct, Lake / Aqueduct, River

[John Campbell]

Aqueduct, {Lake, River} are easier to build than regular ones (20 Shields instead of 80), and have no upkeep (regular are 1 in civ2civ3) or tech requirement (regular need Construction).