Judging by the numbers on those links above. Both the Honda and Renault have seen a significant improvement in power and I would suggest usability. The main difference between 2015 and 16 is that both Honda and Renault powered cars have enough power this year to be able to use DRS successfully, especially if they are on a softer tyre. This was not the case in 2015 when opening the DRS often did nothing at all and a Williams would just power away.
Force India look in desperate straights and the new car looks exactly like the old one. I don't think it has evolved in any measure other then the fact it has a 2016 Mercedes engine. The FW38 Williams was designed around this new front wing they have and just like Red Bull at the start of 2015, it affects your performance if you don't have the correct front wing in use. The FW38 should get better.
The Manor is enjoying that Mercedes engine, look at the difference in Manor's top speeds between 2015 and 2016. 317.8 for Stevens vs 333.2 for Wehrlein . Paddy may well say that they are closer in 2016 but they still aren't anywhere close enough to Mercedes and one can only imagine how fast the RB12 would be if it had a Mercedes engine in it.
Hopefully the Renault upgrade will provide an extra 50hp for Canada. That would makes thing much nicer for anybody with a Renault built engine.