Swine flu is caused by the influenza A virus, specifically the H1N1 strain, rather than any coronavirus.
SARS-CoV-1, MERS-CoV, and SARS-CoV-2 (COVID-19) are all coronaviruses responsible for respiratory illnesses.
Swine flu primarily affects pigs but can be transmitted to humans, leading to outbreaks like the 2009 pandemic.