I feel like those 2 champions have a lot in common now, and like Riot do the same thing with every champion they rework (%health damage coz why not)
Their passive: free shield
Their Q:%health damage on multiple instances
Their W: Protect their allies
Their E: a CC dash
Their ult: a big Nope to anyone trying to get on someone
KONO RUBICK DA4 votesshen is based on where his sword is, it's similar to 
not poppy
L0ve Is Blue1 votespoppy is based on where her shield fall
ModWulf Helhammer1 votesNo, she really isn't
Nauthes4 votesand Rumbles ult = Corki W. Why does corki get it on such a low CD?
Abilities can look similar on paper but its all about how it feels when your using it. And from what ive seen these 2 champions fill different enough roles.
L0ve Is Blue1 votesWell Corki's empowerd W is a better version of rumble's ult...
Dreadlocks1 votesYeah and steered to the jungle now, or hell even support more than top-lane.
1374341 votesWell it generally follows the pattern that Riot likes and has settled on:
Q: Main Damage ability on short(est) cd W: Strong Defense/Utility ability or weaker damage (depending on champ/ intended role) E: More utility/cc or weaker damage (but damage usually stronger or more reliable than W)- often mixed together here R: Whatever fits the role (and for things like tanks/bruisers it is often either a big Nope or a big initiation)
Obviously these are not hard and fast rules, it depends on the kit, and many of the older champions (e.g. Nunu) don't follow it. But if you have something like a blink, damage, and cc/utility spell it is basically guaranteed they would E, Q, and W respectively.