It almost sounds like a branding experiement gone wrong...
Surely - Conditional offer - You need to obtain certain grades to meet the conditions, there is a possibility you might fail.
- Unconditional offer - You're in. You already posess whatever grades needed, there should NOT be a possibility to fail.
It seems a pretty straightforward system as it and any attempt to change these basic meanings would be pretty stupid, if a 'Unconditional offer' cares about what grades you get..then surely its conditional? what with having conditions to entry and everything.