MK drives decisions of how ERAS will look/feel, and Mirsaneli makes decisions on the NH mod; they have widely divergent tastes and I highly doubt MK would agree with the sea/ambient changes to make ERAS look/feel like NH.
I also have no intention of trying to document all the differences between ERAS and NH, because I have never played NH and do not intend to devote time to do so just to document how it might differ from ERAS. ERAS is based on COAS and NH is based on POTC, which are quite different from each other, and that is as far as I'm currently able to describe.
COAS was based on the 2.8 version of the engine, which handled particle effects for cannon smoke much differently than POTC and the 2.0 version of the engine. I did obtain the 2.0 version of particle effects and allowed NH to keep that older way of doing them. Similar for the character dialogs, with 2.8 removing the "head animation" vs. the 2.0 dialog which contained a head portrait of the NPC.
It is possible to change anything in ERAS to match NH, but it is not trivial and I can guarantee that ERAS will not be changed by us to match NH; they will remain different.