Actually, even in Austria there are several different dialects. Similar to germany, even though Austria is much smaller ;o). To take it further: Even in Vienna, were I am living at the moment, there are different dialects, depending on the district. But anyway, you cannot say, that Austrian dialect is similar to Bavarian dialect (never say this to an Austrian!!! ;oD ).
Important to know: In Austria they use quite a lot of expressions not used in germany, and in some cases the gender of words is different (compared to german).