Ardent Seas blends modern naval combat with classical RTS gameplay, featuring Aliens, space lasers, and unholy amounts of missiles
This change is both visual and functional. It loses two of the "Lance" anti-ship missile launchers, and trades it for a single 16-cell VLS, able to fire at most targets. The Main gun is smaller (127mm instead of 203mm), but fires faster. The forward CIWS gun is swapped for a RAM launcher, which are slower to engage missiles, but have better range. And it has gained Torpedo launchers.
Overall the change aims to improve its performance at range, and against submarines, while somewhat weakening it at close range.
And lastly a detail only relevant to naval nerds (like both of us!): The Radars. The old destroyer has an extremely powerful aerial search radar, based on the SMART-L. That's because I ( = Helge) designed it based on the F124 Sachsen-class of air defense frigates.
The destroyer isn't an anti-aircraft ship primarily, so that radar is gone. The TDN cruiser will get it instead. The new Destroyer model has X- and S-Band fixed PARs, and the usual navigational radars. Large spinning radars will be reserved for anti-aircraft ships, like the Cruiser, and also Carriers.