I can't compare the two. I had the Kindle for a week and returned it. The Samsung has one speaker and the sound is mono and plain. Both are inexpensive,low power tablets. But since I have a PC and a laptop,the Samsung is for WiFI travel. You get what you pay for and both are capitated to either Google or Amazon. Hope this helps
If you get the Samsung, you'd probably want to get external speakers for quality sound. I use the Samsung for travel mostly. On the occasion I watch a movie on the Galaxy, it it is better to use earphones. Not sure about the Kindle, but the Samsung has a proprietary adapter for using USB drives. Buy one on ebay for $5 or $20 at Best Buy.
I don't have a Kindle, so can't provide a comparison. But unless you plan to attach external speakers the Samsung sound is somewhat tinny and mono from the single speaker. I connect my wireless running headphones via blue-tooth when I travel and it sounds pretty good for an inexpensive tablet.