Key difference: The main difference between the regular flu and swine flu is the fact that they are caused by different pathogens. Influenza, commonly known as the flu, is caused by the RNA viruses of the family Orthomyxoviridae. Swine influenza, on the other hand, is caused by another type of virus. Swine influenza is caused by the swine influenza virus (SIV) or swine-origin influenza virus (S-OIV). These viruses are any strain of the influenza family of viruses that is common in pigs.

The main difference between the regular flu and swine flu is the fact that they are caused by different pathogens. Influenza, commonly known as the flu, is caused by the RNA viruses of the family Orthomyxoviridae. Orthomyxoviridae are various types of influenza viruses.

Influenza is a completely different infection and is much worse than a common cold. The symptoms of the flu include chills, fever, sore throat, muscle pains, headaches, which are often severe, coughing, weakness, fatigue and general discomfort. Most flu symptoms usually do improve over two to five days. However, one can feel run down for a week or more. Influenza can be prevented with a flu vaccine.

Furthermore, the flu can occasionally lead to pneumonia, either direct viral pneumonia or secondary bacterial pneumonia. A warning sign, if the flu is transgressing to pneumonia, is when the affected person appears to be getting better and then relapses with a high fever. This is a warning sign for bacterial pneumonia. Another warning sign is if the person starts to have trouble breathing.

Swine influenza, on the other hand, is caused by another type of virus. Swine influenza is caused by the swine influenza virus (SIV) or swine-origin influenza virus (S-OIV). These viruses are any strain of the influenza family of viruses that is common in pigs. Essentially, swine influenza is a type of flu that affects pigs or swine. However, a strain of these viruses mutated and became able to affect humans. Hence, it passed on from a pig to a human, who in turn spread it to other humans, through human-to-human contact.

Swine influenza is also known as pig influenza, swine flu, hog flu and pig flu. When this flu infects humans and causes human flu, it is called zoonotic swine flu. As of 2009, the known SIV strains include influenza C and the subtypes of influenza A known as H1N1, H1N2, H2N1, H3N1, H3N2, and H2N3.

In human, the symptoms of the swine flu are similar to the regular flu. The symptoms include chills, fever, sore throat, muscle pains, severe headache, coughing, weakness and general discomfort.

However, instances where swine flu affects humans are very rare. In fact there have been only 50 known transmissions of the flu from a pig to a human.  The problem arises when the infected person passes on the virus to other people through human-to-human contact. In 2009, the outbreak of the H1N1 virus was declared by the World Health Organization to be a level 5 pandemic, the second highest level.

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