In regards to amino acid sequence and composition of proteins, SARS-CoV2 bears many resemblances and similarities with SARS-CoV but there are certainly significant differences as well:

• The 8a accessory protein is absent in SARS-CoV2 but is present in other SARS-CoV.
• The 8b accessory protein’s amino acid sequences is longer in SARS-CoV2 with 121 amino acids compared to the 84 amino acids in other SARS-CoV.
• The 3b accessory protein amino acid sequence is considerably shorter in SARS-CoV2 with just 22 amino acids compared to the 154 amino acids seen in other SARS-CoV.