Upper frontal plate and lower frontal plate were practically unchanged. The 203mm thick weld in-between is gone but that's a small change. The turret armor however was significantly improved. Earlier the turret armor was 150mm to 190mm thick but now - taking the complicated shape into account the thickest parts of frontal turret are 280-350mm thick (effectively). The mantlet is now 570mm thick (together with armor behind it), earlier it was 360mm. The mantlet itself even got a bit bigger.
Guess this is a good excuse for me to stop neglecting the tank and finish my British HT grind.