The most obvious difference between the two is resolution: that the Fire TV Stick has a max resolution of 1080p, whereas the Fire TV Stick 4K supports 4K movie as well as HDR10 and Dolby Vision technology. The Fire TV Stick 4K also has an upgraded processor compared to elderly Fire TV devices, so that it will have noticeably faster and smoother performance. Otherwise, both streaming sticks have 8GB of RAM, 802.11ac dual-band MIMO Wi-Fi, and Alexa voice control support through the remote.
Speaking of Fire TVs, Amazon has heavily discounted many of those streaming devices, for example, Fire TV Stick and also the Fire TV Stick 4K. For Prime Day, the Fire TV Stick with an Alexa Remote for $14.99 (down from $39.99) or a Fire TV Stick 4K with an Alexa Remote for $24.99 (down from $49.99). Fire TV Sticks are the most economical streaming devices from Amazon, but these Prime Day prices are both new lows for the respective devices.