It has to do with the way they are rating power to appeal to different markets. Two similarly priced receivers from their RX-V and HTR lines are virtually identical but the latter is rated at 1kHz and higher distortion for a bigger power number than the RX-V rated at full bandwidth, lower distortion.
Its kinda a marketing game since they assume the RX-V line will be sold at retailers who attract more home theater savvy shoppers and the HTR line would be sold at retailers attracting more of the home theater enthusiast crowd.