What sound differences are you looking for? What differences do you notice?

Multichannel PCM 5.1 audio is uncompressed/lossless and requires an HDMI-eARC port connection to the Sonos Soundbar. Dolby Digital/Plus 5.1 audio is compressed/lossy, lower-bandwidth format that has been optimized for use with streaming services and it just requires an HDMI-ARC port connection or eARC, or you can use an optical connection with DD 5.1 audio. I personally struggle to hear any huge difference although with Sonos soundbars McPCM audio may sometimes sound quieter than DD, but I just choose to increase the volume if ever I encounter that issue. Otherwise the output sounds the same/similar to my ears. Both McPCM and DD+ audio can support Atmos audio too. That includes height channel audio and metadata, which directs/controls where the audio content should be played and their levels etc. (see attached, which I came across online)

Thank you very much for your answers.I had to put on a Netflix movie "Mission Impossible" and that's where I noticed that the Dolby digital plus 5.1 sound sounds louder, as you mentioned.before with my old samsung tv i didn't have that option, but with my new tv i can choose multichannel pcm2.1/dolgi digital 2.1, multichannel pcm5.1/dolby digital plus 5.1.As for dialogues, I have not yet observed differences, since I just bought the TV.thank you.