I guess that's a very broad way to describe it. Simplifying things even further, "power" and "attack" have the same function, we could probably just call them "round-winner..." Likewise, "damage" and "life" have the same function, so we could probably call them "gap."
However, these pillars are too basic to give any idea of what a card's *role* actually is. Roles are more complex and can combine the functions of multiple pillars, or apply them in indirect ways.
Some examples of roles:
Wall: This card is difficult to beat. Its typical role is to deny damage indirectly, either by forcing pills, or by beating an opposing card for low pill cost. EX: Chiara, Mona
Threat: This card combines average or better round winning power with average or better gap. It is usually too ambiguous to easily read, as it is not too high-impact to bluff, but too high-impact for your opponent to let it through without consequence. EX: Murray
Nuke: This card gaps extremely well. 4 or 5* nukes sometimes have above average round-winning power as well. 4 or 5* nukes that lack additional round-winning power usually gap for hilariously high amounts. EX: Ongh
Dual purpose: (For lack of a better name) This flexible card combines some form of DR/defeat ability with decent gap. Because of this, it can play multiple roles against most hands. Ex: Marina
There are other roles -- Mitigating, Fork, etc... not enough space to describe each one.