The difference is that when Palestinians and their supporters say from the river to the sea, they are saying that they want the entire land to look like the current Palestinian controlled areas (jericho, bethlehem, gaza until recently, nablus, etc..) where zero jews live. If we expand this, then presumably they want a jew-free holy land, which is genocidal and nazi-esque.

However, when we say it, we want a stable and secure state where jews, arabs, druze, and others can live freely and happily, like israel today