HD, Full HD and 4K are resolution categories; they do not by themselves describe bitrate, source detail, colour quality or playback stability. The actual source and device conditions determine the result.
What resolution describes
Resolution describes the dimensions of the video image. A display can scale a lower-resolution image to fit its panel, but scaling does not restore detail that was never in the source.
Why similar labels can look different
| Factor | Effect to check |
|---|---|
| Source detail | Whether the image was captured or supplied at that quality |
| Compression | Detail loss and motion artefacts |
| Decoder | Whether the device can decode the source smoothly |
| Display | Aspect ratio, scaling and picture processing |
| Network | Whether data arrives consistently during playback |
What to check on a trial
Compare several priority items on the final screen and normal connection. Confirm selected 4K availability for the actual account. This website does not claim every item is delivered at every resolution.