WASHINGTON — David Holmes, a career diplomat and political counselor to the United States Embassy in Ukraine, and Fiona Hill, a former Europe and Russia expert at the White House, schooled lawmakers on Thursday on the United States’ geopolitical relationship with Ukraine and provided some new details about the efforts to pressure Ukraine to announce investigations into President Trump’s political rivals.

They both highlighted their apolitical and nonpartisan expertise and experience in foreign policy, a direct contrast to the witness a day earlier, Gordon D. Sondland, the United States ambassador to the European Union. Mr. Sondland is a wealthy Republican donor with no diplomatic experience before his 2018 appointment to the plum post in Brussels.

Here are some key points from Thursday’s testimony.

Hill differentiated between a ‘domestic political errand’ and ‘national security foreign policy.’

Responding to questions from Republicans, Dr. Hill explained the crux of the issue at the heart of the impeachment inquiry — the United States had two separate agendas operating in Ukraine, yet those involved in each viewed theirs was the only one.

Dr. Hill said she and other career foreign policy officials were frustrated with what Mr. Sondland was doing outside the normal channels of interagency coordination.

Hill: “What I was angry about was that he wasn’t coordinating with us. I’ve actually realized, having listened to his deposition, that he was absolutely right. That he wasn’t coordinating with us because we weren’t doing the same thing that he was doing. So I was upset with him, that he wasn’t fully telling us about all of the meetings that he was having. And he said to me ‘But I’m briefing the president. I’m briefing Chief of Staff Mulvaney. I’m briefing Secretary Pompeo, and I’ve talked to Ambassador Bolton. Who else do I have to deal with? And the point is that we have a robust interagency process that deals with Ukraine. It includes Mr. Holmes, it includes Ambassador Taylor as the chargé in Ukraine, it includes a whole load of other people. But it struck me when yesterday, when you put up on the screen Ambassador Sondland’s emails, and who was on these emails? These were the people that need to know. And he was absolutely right. Because he was being involved in a domestic political errand. And we were being involved in national security foreign policy, and those two things had just diverged.”

Dr. Hill thought Mr. Sondland’s goal of getting President Volodymyr Zelensky of Ukraine to announce investigations into Mr. Trump’s political rivals was trivial and contrary to longstanding efforts regarding Ukraine.