They are also equally alike in that both use celebrities to promote their policies. And celebrities use BOTH to promote themselves.
The UN general assembly is rather infamous for inviting celebrities to speak before it. Leo DiCaprio spoke about climate control at the UN...before getting on a private jet to fly off on holiday. TRUE. George Clooney had been angling for a full assembly speech for the longest time, but only got a security counsel speaking gig - and then resigned from his 'peacekeeper' position. He said it was because he no longer had time - he'd never spent much time on it, anyway. Likely, it had everything to do with the UN not giving him a more high-profile part in UN PR.
The UN and UNICEF use and are used for PR.
Jolie is probably one of the few UN/UNICEF celebs whose role is completely PR-less - and I say that not being her biggest fan - at all. The number of trips she undertakes is 10x that of other ambassadors. And many of her trips are not reported - except in UN circulars.