Yes, Sardinian is totally different from Italian and is infact directly descended from Latin, infact many words are very Latin sounding. This language (because in all effects, it is a proper language per se, as opposed to a dialect which most other Italian regions have depending on where they are...eg. Romanesco (Rome), Genovese (Genoa), Napoletano (Naples) etc.) varies from north to south, but are very similar.
Having said all that, my Italian half is not Sardinian (I was born in Genoa from Piedemont/Tuscan lineage...mixing again! ) and I'm also slowly learning Sardinian (Campidanese), though I've noticed (thanks to my Spanish half and knowledge of the language) that there are many Spanish terms and sounds in the Sardinian language and that's beacause the Spaniards conquered Sardinia and settled here for 400 years before been ousted.