Accents are different, even in China, there are still many kinds of accents.
In writting, Taiwanese use troditional Mandarin while simplified Mandarin is used in China. TM is hard to write but more logical, on contrary, SM is easy to write but not that logical.
Besides, Taiwan has other language that used in the mass, Taiwanese, which is transformed from Southern Min(閩南;min3 nan2). It's hard to explain in English, but fujian's southern min language is able to communicate yet distinct with tainwanese southern min language(Taiwanese).
Around 80% taiwan citizen know Tainwanese so we use a lot of taiwanese words mixed with chinese, it also makes difference from China.