I have a Sony 75" TV and I can tell you there is little, if any, difference between the HD channels via aerial (and that includes the Freesat signal), and BT's Multicast stream. But I have adjusted the settings manually for each HDMI source that I use.
I did a scan of BT’s multicast ports recently and whilst it is encrypted, it’s still possible to get some data for comparison.
Using data from Digital Bitrate to compare, all IP channels have more than double the average of the broadcast platform and that’s just SD… HD goes between 8 and 10mbps.
Clearly they’re using a different codecs etc but the resolution is also higher on the IP channels, which should help too.
Not sure about the SD streams but HD are 1080p @Matomo
To me the SD channels look like they’re in higher definition than Freeview so I’m curious.
Freeview HD channels are 1080i, so a slight improvement on BT.
Freeview SD is 576i and the BT IP Freeview channels are higher so probably closer to 720i.
1080p is a lot better than the 1080i that Freeview use.
I copied this from a website
Further, 1080p is generally more vivid and realistic, which most people prefer. The higher image quality (around 60% better) comes from the fact that in 1080i, the even and odd rows of pixels aren't displayed simultaneously. In other words, 1080i is similar in quality to 720p