4 things pop out to me in this comparison.
1. the narrower/tighter bodywork which can be seen very well at the sides of the HALO device,
look how much tighter it is and how much more air can be channeld to the rear.
the amount of 'white' (open space) seems more or less the same but the RB16 has much bigger
suspension fairings, so plays with the eyes.
2. next, the much narrower nose creates much more potential or lets say much less restriction
for the use of 'flaps/cape' 'under' the nose compared to the RB15.
3. third, the interesting nosecone design allows for a much narrower S-duct and as such surely will
improve flow around that area.
4. as mentioned, the gigantic brake ducts at the front, is just staggering compared to the RB15.
lastly there are some other areas, it looks like the sidepod inlets are even smaller then last years.
perhaps it's channeled better, i don't know, but i get the impression it's even narrower,
so cooling must be even less than an issue. then again, this is a comparison of the launch RB15,
and not the AbuDhabi version and i'm not sure whether that area has been altered.