The H4 is part of the H Series "hybrid" discs that fall perfectly between distance and fairway drivers. The H4 is a less stable hybrid with considerably more glide and a softer finish than its predecessors; H1, H2 and H3. The H4 will hyzer flip to flat, turn slightly to the right, and then finish left.
The 400G series is the regular 400 plastic with a shot of adrenaline. It is the base 400 plastic mixed with another resin that give the plastic a slightly different feel than the base 400 series. The additive also makes the disc more durable and requires more time to break it in.