The reality is that there is no such thing as the "regular flu virus." They are all sort of cousins so there are hundreds of different variations on the flu "theme." Some are nastier than others. They are usually categorized into influenza A, B, and C, with A being the worst of the three.
When you are getting a flu shot, you are getting a vaccine against what is thought to be the most prevalant of the flu bugs for the year. This still leaves you suseptiable to all the other variations, which is why you can still get the flu even after having a shot.
The H1N1 virus is not fundamentally different from other flu's, it is just a particularly nasty strand for some people. Most of us who get the H1N1 virus will show the typical flu symptoms and fight it in the same way we would any other flu. The problem is that for some people this flu will prove deadly. Of course, every flu outbreak is deadly for some people, usually individuals who are already sick, have compromised immune systems, or are very old/young.
I have read that this is a "novel" stand of the virus:
Arand Kumar, intensive care expert at the University of Manitoba, Winnipeg, Canada, said "this pandemic is like two diseases; either you're off work for a few days or you go to hospital, often to the intensive-care unit (ICU). There's no middle ground."
That seems to be the real interest in this particular flu...most people who get it behave as if they had gotten any other flu. But a few react very badly to it.
Flu is a shortened name for influenza epidemic caused by influenza or flu virus. There is nothing like a "regular flu virus". There are many different types or strains of strains of flu, and new ones keep on developing. The H1N1 virus is a sub type of virus within the category called influenza A. Within H1N1 also there are multiple strains such as swine flu and bird flu.
Influenza A strains are categorized according to two proteins found on the surface of the virus. These are hemagglutinin (H) and neuraminidase (N). Although there are many subtypes of H and N in viruses in other animals, in humans only H1,H2,H3 and N1 and N2 are common.