Min/Max Boards

Volibear and ursa actually fulfill surprisingly different roles in their home genre, despite being bears, and also have only superficial similarity in terms of abilities while having significant differences in application of those abilities. Volibear is a disruptive frontline tank/fighter, while ursa is alternately a beefy assassin or melee carry.

Earthshock and Majestic Roar are both pointblank aoe abilities, but earthshock is inferior; MRoar has the ability to interrupt channels and has a key interaction with Rolling Thunder that vauses it to deal significant damage.

Overpower and Frenzy appear similar on paper, both giving attack speed, but Overpower is a castable buff that has a duration longer than the cooldown which leads to Ursa blink daggering onto you and hitting you with 14 swipes in the span of 3 seconds which can delete basically anyone and frenzy is a two part ability that gives attack speed the longer you're in combat with someone and then has an execute on the bite.

Fury Swipes and Thunder Claws are both OnHit effects that ride on basic auto attacks, but they work differently: fury swipes adds damage to all following attacks and stacks infinitely. Thunderclaws causes your basic attacks to cast Chain Lightning and hit every target in a fairly generous aoe, but is only active for a brief window.

The final abilities (volibears Rolling Thunder/Chosen of the Storm and Ursa's Enrage) dont directly counterpart each other, though i guess you could argue that Enrage and Chosen of the Storm could be considered to fill similar roles making the character deceptively tanky.

Tl;dr: While both are Bears that are similar and will both claw off your face, the actual execution of how they claw off your face is different enough that i don't think they're interchangable.