The difference is because hydroelectric generation depends on currently existing rivers, damming them and turning them into electricity sources has to change th

The difference is because hydroelectric generation depends on currently existing rivers, damming them and turning them into electricity sources has to change the natural ecosystem in the river. For pumped storage, we can essentially build it anywhere there is an elevation change. So we can avoid harming river ecosystems where they naturally exist and create pipes and tanks where it would be the least damaging to the ecosystem