Does Roku support different versions of the Youtube TV app on different Roku streaming sticks? My son just bought the newer 4K+ streaming stick and the Youtube Live Guide looks different from what I get on my older streaming stick +. I don't know what version is on the newer stick but the Youtube TV version on my older stick is 2.22.
The model numbers of the two sticks may have something to do with it as well as the Roku software version and/or the Youtube TV channel version.
TL;DR: Google (not Roku) uses different external/platform versions and internal/UI versions for its YT/YTTV apps for different Roku models & YT/YTTV accounts.
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External/platform version: Highlight YTTV app, press Options (*):
Specifically, they have 4 external/platform YT/YTTV app version tracks for different Roku models/model ranges.
1) Latest model(s): 2.22 (this version track usually only exists for a short time (1-3 months) following the release of the latest Roku models, then combines with 4K/HDR)
2) 4K/HDR models: 2.22/2.21 (this track includes "latest" within 1-3 months after "latest" release)
3) Non-4K/HDR models: 2.20
4) Legacy models: 2.0
5) Roku TVs: Depends on brand/model - above 4 categories apply
The latest/greatest models get the newest YT/YTTV app version, the 4K/HDR models get the next highest, non-4K/HDR models get the next, and legacy models have the lowest version.
YT/YTTV versions/builds are also RokuOS firmware version/build dependent on occasion (meaning certain YT/YTTV version/builds are only available with certain RokuOS versions/builds; upgrading or downgrading RokuOS can/may/does result in a different YT/YTTV version/build).
However, occasionally models in the latest and/or 4K/HDR categories are inverted/reversed/mixed, such that the "latest" 4K/HDR models have a lesser version/build (2.21 currently), and "older" 4K/HDR models have a greater version/build (2.22 currently) - such is the case currently (e.g. 3810 (2017/2019) has 2.22, but 3820 has 2.21)
Internal/UI version: Open YTTV app, Account/About/App version/Version:
Google also uses a "universal" (downloaded at load time) internal/UI version so that their apps have a consistent look/feel across different platforms; however, the options/appearance of this internal/UI version are dependent upon the external-platform version (e.g. 4K, HDR, Speed).
This internal/UI version can also be dependent on account - Google is testing a newer (soon to be released) UI for YTTV that is only available for some accounts, which is most likely why your son's SS 4K+ YTTV app UI looks different than the YTTV app UI for your SS+ (his YTTV account is "Beta testing" the new UI). Eventually, all accounts will get the new Live Guide UI.
Certain internal/UI version features/functions are only available with certain external/platform versions & models (e.g. Speed settings are only available for 4K/HDR-capable models using YT/YTTV app versions 2.22 & 2.21 - non-4K/HDR-capable models do not get the Speed settings, nor do 4K/HDR models using version 2.20)