I’m not seeing how warlords are identical to bards. Leaders in general seem capable of buffing and healing, and in addition has their own respective area of expertise:
Clerics can strike enemies with a variety of radiant attacks, turn undead, and enact deity-specific powers.
Warlords can restrict or enhance movement and grant additional attacks to allies in different tactical situations.
Bards will presumably be able to pull off a number of charms, illusions, and/or other manipulative tidbits.
At least, that’s my guess of how they will be clearly distinguished. I see similarities between warlords and bards in that they both are leaders and fluff-wise work wonders by inspiring others to greatness, but that’s about it.