Viruses are really on a different scale because they evolve so quickly. For viruses in the same family, you can make comparison on the nucleotide level. However, once you move outside of families, you can really only make comparisons at the protein (amino acid level). And when you are talking proteins, <30-40% similarity between viral families is common. The difficulty with studying viral taxonomy is the absence of highly conserved genes that all viruses have. It is only within the past 10 years that there's been development of a "tree of life" for viruses, and even that is very incomplete. That's different for living organisms like archea, bacteria, and eukaryotes (animals, plants, fungi, etc) where common genes do exist (the ribosomal subunits are most often used for that type of comparison).That's nuts I thought they were pretty similar. I'm shocked that two coronaviruses can be that genetically different. Isn't that like the difference between a worm an human? Or is that a different scale because it's genes vs nucleotides?
If you want to get into a rabbit hole, you can read about viral dark matter. Scientists have really powerful sequencing technology that they can sequence every DNA/RNA molecule present in a sample. They can easily determine that many of the molecules originate from humans, bacteria, viruses, plants, etc. However, nearly 50% of the genetic material doesn't align to any known organism/virus. It is presumed this leftover genetic material is from novel viruses and microorganisms, but scientists lack the "language" to know what they are. It is very similar to dark matter. The equations and math suggests that dark matter exists, but physicists lack the capacity to actually know what dark matter is.