How do Austrian German and German from Germany differ from each other?
What I noticed is that Austrians pronounce “r”, “t” and “ei” different than Germans. People say “Grüss Gott” even if they’re not religious and if not all many of them use it. I once heard that an old man pronunced “zwei” as “zwo” or “tswo”. That was interesting.
A native speaker or the ones who speak the language or lived in Austria can explain it better. You can watch the funeral of Otto Habsburg (2011). Priests speak with pure Austrian accent (I guess)
I see, and in terms of the type of German that is taught in courses and elsewhere, what variety of German is that? Is it a mix of German from Germany and Austrian German? Would you call it something like Standard German, something that is present in both countries? I was just curious about the German that you would encounter in a course or online learning, such as here at LingQ.
It’s called Hochdeutsch. Hochdeutsch was derived from Hanoverian accent. German that is taught in courses is not a mix of different accents because there are a lot of accents of German and some of them can be considered different languages, I think. Actually there is no such a thing like Germany German. Every region has its own accent. If you listen to news (from Germany) you would hear Hochdeutsch (Standard German) but it is not present in both countries however it is taught in courses and foreigners speak it. Native speakers speak regional accents but if they notice that you’re a foreigner (they notice me without the necesity of warning them that I am not German 
) they speak Hochdeutsch.
I was taught Hochdeutsch and the courses on LingQ are mostly in Hochdeutsch. There is one contributer, I guess his name is Reinhard, who speaks Austrian accent. If you search the word “Austrian” on LingQ German Library you can access it.
People mostly strugle to understand Austrian, Schwaebisch, Swiss German and Bavarian German. I only can understand the accents from North - Northwest regions. It’s not that difficult to understand people from different regions but if they speak slowly, if they don’t I really can’t understand them and try to keep smiling.
Edit: Wait for other members’ comments. They know better than me.