It's pretty similar, I have another comment on this thread talking about this so I'm going to try not to repeat myself but a basic difference is that 'shareware' is a much broader term. Shareware can be anything from fully functional 'nagware' to a useful product with extra features in the pay version to a product with limited features with the limits removed in the pay version. And there are probably another 30 variations.
Freemium is a web service where ideally the free version is useful and you pay for certain additional features or a reduction in the limits of existing features. This makes the model like that of some shareware. You're generally buying a service so the something-ware name becomes even less sensible.
That's not to say that 'freemium' is not one ugly gargoyle of a word that I hope drops into the same oblivion pit where we left 'folksonomy' and other monsters.
Freemium is a web service where ideally the free version is useful and you pay for certain additional features or a reduction in the limits of existing features. This makes the model like that of some shareware. You're generally buying a service so the something-ware name becomes even less sensible.
That's not to say that 'freemium' is not one ugly gargoyle of a word that I hope drops into the same oblivion pit where we left 'folksonomy' and other monsters.