Jean-Claude Juncker is from Luxembourg. He is the President of the European Commission.
The President of the European Commission is the head of the European Commission (the civil service of the executive branch of the European Union, the function of which is to apply and enforce the Treaties). The President of the Commission is responsible for allocating portfolios to members of the Commission and can reshuffle or dismiss them if needed. They determine the Commission's policy agenda and all the legislative proposals it produces (the Commission is the only body that can propose EU laws).
Donald Tusk is from Poland. He is the President of the European Council.
The President of the European Council is a principal representative of the European Union (EU) on the world stage, and the person presiding over and driving forward the work of the European Council. This institution comprises the college of heads of state or government of EU member states as well as the President of the European Commission, and provides political direction to the European Union (EU).
Is that clear? In the run up to Brexit discussions, the distinctions and partitions of responsibility remind me irresistibly of:
Miles Massey: Baron von Espy, what is your profession?
Heinz, the Baron Krauss von Espy: [in outrageous French accent] Silly man. I am a baron.
Miles Massey: Yes, but do you not also hold a day job? Paying job. A, uh, a square job.
Heinz, the Baron Krauss von Espy: Well, one has to live. I am the concierge of Les Pantalons Rouges at Bad-Gadesbourg in the canton of Uri.
Miles Massey: And what does that job entail?
Heinz, the Baron Krauss von Espy: I satisfy such requests as the clientele may present.
Miles Massey: Towels, ice, et cetera?
Heinz, the Baron Krauss von Espy: We have bellmen for that. No, no, no. Such requests that, were you at home, you would address not to your valet but to your majordomo.Adults In The Room: My Battle With Europe’s Deep Establishment by Yanis Varoufakis is likely to be essential reading over the next weeks and months.