Why pick Nautilus over Tahm Kench

So, the title.

Can anyone who mains either champ and preferably plays both explain to me when they would pick the former over the latter?

Tahm has way more damage, the same amount of cc with more stickyness, and is about twice as tanky, has a suppression and an ally moveable zhonya, with an almost global teleport for his allies.

Nautilus has a rooting passive with a cooldown on its target, an aoe slow, a hook to setup his passive (and escape), and a point-click knockup, but does almost no damage (except if ap).

Yes, I realise Tahm's cc is almost completely melee and Nautilus can be a threat at a greater range but I would like to know regardless if there is something I am missing.