Sorry if this breaks the rules - I've been reading up on the Habsburgs in my free time and there are aspects of their rule and realm that confuse me.
I am aware that Charles V split his kingdom between his brother (Austria) and his son (Spain, Italy). There then emerge several terms relating to this:
The Habsburg monarchy: referring to the rulers over the Archduchy of Austria - > Austrian Empire - > Austria Hungary
The Spanish Habsburgs: the rulers over the Spanish territories aka Spanish empire
The House of Habsburg: referring to both these branches but they also ruled the Holy Roman Empire for a period of time until its end (thanks to Napoleon), of which the Habsburg territories were partially within?
So was the emperor of the holy roman empire also the ruler of the austrian territories, the spanish territories, both, neither and was just another member in the family, or did this vary depending on who was elected emperor? And how did this arrangement of two overlapping empires work? Sorry if this is a vague question.
Do also let me know if my understanding of the various aspects of Habsburg rule as articulated above is correct
The Archduchy of Austria very specifically refers to the provinces of Upper and Lower Austria that Hapsburgs had ruled since the late 13th century. The thing to keep in mind about the Hapsburg possessions, especially in the time before the reign of Joseph II in the late 18th century, is that the "Hapsburg lands" were all discrete territories with their own laws and governing bodies that happened to share a dynastic ruler: so the Hapsburg Archduke of Austria was also the King of Bohemia and the King of Hungary. Usually. Until dynastic inheritance issues led to conflicts (the question of who was the proper King of Bohemia is what kicked off the Thirty Years' War in 1648, and Prussia's seizure of Silesia - in effect not recognizing Maria Theresa's inheritance of the Duchy in 1740, kicked off another generation's worth of wars).
The office of Holy Roman Emperor was, from the 13th century on, an elective monarchy, chosen usually by seven prince electors (the Archbishops of Mainz, Koblenz and Trier, the Count of the Rhenish Palatinate, the Margrave of Brandenburg, the Duke of Saxony, and the King of Bohemia; other prince electors were added in the 17th-19th centuries).
From 1440 until 1806, with one exception in 1742-1745, whoever was Archduke of Austria got elected as Holy Roman Emperor (it helped that they were almost always also the King of Bohemia and one of their own electors). In 1804, Francis II, the Holy Roman Emperor, declared himself Austrian Emperor as a reaction to Napoleon crowning himself Emperor of the French. This made Francis emperor over Hapsburg lands in his own right, and a couple years later the Holy Roman Empire was dissolved. The western, German-speaking parts of this empire were included in the German Confederation after the Congress of Vienna in 1815.
The Austrian Empire was reorganized in 1867, following its defeat at the hands of Prussia and Italy, the dissolution of thr German Confederation, and the unification of Germany and Italy. The Kingdom of Hungary was elevated to effectively self-governing status, with the Austrian Emperor also serving as King of Hungary. The "Austrian Empire" effectively referred to those parts of Austria-Hungary that were not governed directly or indirectly by the Kingdom of Hungary.