I have both models available to me -- which one is newer?
They are the same device. The old identifier RW used to mean Retailer Walmart.
The 3820R2 is now sold both at Walmart and on the Roku website.
https://www.roku.com/products/roku-streaming-stick-4k
https://www.walmart.com/ip/Roku-Streaming-Stick-4K-HDR-with-Roku-Voice-Remote/913284187
Here is an ebay seller offering the 3820RW2 ebay
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The 3820R2 and 3820RW are the same device, same Voice Remotes, same price, same everything; just different retailer markings to indicate the point of sale.
@avensis44 wrote:The 3820RW2 is probably the newer and potentially better model
Nope, see the post above yours. There's no difference between the two models, none.