Hull itself offers side armor that can soak damage without passing damage to hull's integrity. Also offers better resistance profile and some protection against Ap. Bit of misplay there, should have stayed lower to protect softer belly from ground units.

Better, more efficient emitter with various firing modes, fast tracking rapid fire pulse (better trigger on my part wouldn't hurt) and slow tracking high damage beam. Also higher affinity = faster build up for Core effect, in this case burn DoT.