F5 is a high speed, stable to under stable fairway driver. It is designed for all skill levels and flies extremely far and incredibly straight. The F5 will turn up slightly when thrown hard it will go into a long glide before finishing gently to the stable side.
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.