One important difference is that penicillin is useful against a wide range of bacteria. I'm not sure, but the article says that this new drug is useful only against influenza.

There are many antiviral, but they are artificial and they are targeted against certain families of virus (for example, acyclovir is only useful against herpes and similar virus http://en.wikipedia.org/wiki/Aciclovir ).

This is the first natural antiviral, but it's not a wide range antiviral.