Amazon offers the Kindle Fire 7" model in the HD version and the HDX version. Depending on a buyer's preferences, he or she could opt for the HD or the HDX version, since they are both affordable and powerful tablets.

The HD version measures in at 7.5 x 5.4 x 0.4 inches. That is compared to the HDX which measures in at 7.3 x 5.0 x 0.4 inches. That is not an extreme change between the two models. The weight of the HD is 11.9 oz. The HDX model was able to shed a couple of ounces and only weighs in at 10.7 oz.

Internally, the processor is the big difference between the two devices. The HD had only a 1.2 GHz dual core processor while the HDX upgraded to a 2.2GHz quad-core Snapdragon 800 processor. 

The HD's display is, as the name suggests, high definition quality. It is a 1,280 x 800 IPS LCD that is capable of displaying HD content. With the HDMI output, content can be displayed on whichever HD screen a user chooses. The HDX display improves to a 1,920 x 1,200 LCD. That matches the Nexus 7's display and beats out the iPad mini. 

Battery life on the HD almost hits 10 hours at 9:57. The HDX improves battery life to 10 hours and 41 minutes.

The HD will only offer two storage options, either a 16 GB model or a 32 GB model. The HDX will offer three storage options, the 16 GB, 32 GB or 64 GB models. Buyers of either the Fire HD or Fire HDX can opt-in for Amazon's "Special Offers" advertising program to allow for lower prices of the tablets. The program adds built-in advertisements to the tablet.

The HD offers Dolby Digital Plus quality audio. The HDX moved the speakers up to the top of the device, meaning the sound has less of a chance of getting muffled. 

The Amazon Kindle Fire HD can be purchased from Amazon $139. The Amazon Fire HDX can be purchased from Amazon for $179.