Holy Roman Empire Is Basically Germany , Austria and Prussia. Most of Prussia is NOT in Germany anymore.
There was a competition who would Germany re-unite under Austria or Prussia and Prussia was the winner and Austria was left out.
Germany was greatly shruken after WWI and WWII and much of prussia became part of Poland and Russia (Many Cities were known by German name now have a different name like Danzig which is now Gdansk Poland ) and Koningsborg which is now Kalingrad Russia