Bavarian Course for English Speakers
This is the first post dedicated to the creation of a Bavarian for English speakers course. Please upvote and comment. Maybe someday we will have it!
It's a dialect. That means that yes, it is different, but not drastically. It further means that there is no standard, i.e. there is not one Bavarian dialect, as there is not just one Hessian, Saxonian, Swabian, Palatinian, Low Rhinish, Bergian etc. dialect.
In today's state of Bavaria, there are three families of dialects: Bavarian, Frankonian and Swabian, with smaal regions where Allemannian and Hessian are spoken. The Bavarian dialects themselves fall into three subfamilies: northern, central and south Bavarian. For an idea of the complexity, have look here.
According to Lrtward's master post, Duolingo have already stated that they won't do courses on dialects even in languages were the dialects are as massively different as they are in Arabic. While German dialects also aren't always mutually intelligible, the vast majority of German native speakers are able to speak some form of Standard German. If you really want to learn a regional German dialect, you're probably going to have to move to that region and learn it from immersion. A few additonal resources:
-Bavaria's biggest radio and TV station (They will have some programmes in the Bavarian dialect, I just don't know which ones): http://www.br.de/index.html
-A website on German dialects, could be useful to learn the regional expressions: http://www.atlas-alltagssprache.de/
Like others already said German dialects are not standardised, but depend a lot on the region. My Swabian grandma can quite accurately say where a Swabian speaker comes from. Bavarian is just as diverse.
If you want to try immersion to understand it better I'd suggest trying the "Tatort" episodes set in Munich with Leitmayr and Batic. Tatort is a very long-standing, famous German crime show rotating through different cities and their police teams, the inspectors, suspects and witnesses often speak the dialect of the region, some with heavier dialect than others. The Munich team has been solving crime since the early 90s and with 2 or 3 feature-film length episodes a year you'd have quite a bit to watch. :)