As a fellow alternative Ubuntu user, one additional difference is the LTS support schedule which is shorter for Ubuntu alternatives. For example, Xubuntu 24.04 is supported until 2027, while Ubuntu 24.04 is supported until 2029.
Interestingly, as I understood it, when a release such as Xubuntu goes out of support it does not stop getting updates that are not specific to that respective flavor, so in a way you still have some indirect support, but feels a bit like a gamble.
One nice benefit for optical media is that it's hard read only by default. This makes it easy to ensure the install media does not get corrupted by overwrites or malware.
Interestingly, as I understood it, when a release such as Xubuntu goes out of support it does not stop getting updates that are not specific to that respective flavor, so in a way you still have some indirect support, but feels a bit like a gamble.