Blu-ray and 4K are totally different concepts but when used in DVDs they can be compared together.
How is 4K Blu-ray different from regular Blu-ray? - Quora
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I tested Blu-ray vs Netflix and Disney Plus on the same movies, and the biggest difference surprised me
Andor,' 'Moon Knight,' 'Obi-Wan Kenobi' Bow on 4K, Blu-ray
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馃捒Discotek Media on X: 4k discs have various differences from standard Blu- ray (no branching, no SD interlaced video, no galleries, etc.), so the release is a bit different than the original Blu-ray
Which is Better: 4K Ultra HD vs. Blu-ray with Differences
Blade Runner 2049 4K UHD (2017) - Page 336 - Blu-ray Forum