Short answers, pulled from the story.
The Jewish diaspora refers to the dispersion of Jews living outside the Land of Israel. It is traced to two ancient exilic events: the Assyrian conquest of the Kingdom of Israel in 722 BCE under Sargon II, and the Babylonian conquest of the Kingdom of Judah in 586 BCE under Nebuchadnezzar II. By the Second Temple period, Jonathan Adelman estimated that around 60 percent of Jews already lived outside the homeland.
Diaspora and galut draw from two completely different lexicons, as Stéphane Dufoix concluded in his survey of the textual evidence. Diaspora, which entered English usage as late as 1876, can carry a positive nuance of geopolitical dispersion while maintaining cultural ties to a place of origin. Galut is a religious-nationalist term implying exile caused by collective sins, awaiting divine redemption, and conveying a deeper sense of uprootedness.
The First Jewish-Roman War, crushed in 73 CE, destroyed the Temple in Jerusalem and led to the sale of approximately 97,000 Jewish captives into slavery, according to Josephus. A further 30,000 Jews were reportedly deported to Carthage. The Bar Kokhba revolt of 132-136 CE resulted in Jews being forbidden entrance to Jerusalem on pain of death, except on Tisha B'Av, and significantly expanded diaspora communities.
Ashkenazi Jews coalesced in the Holy Roman Empire and Eastern Europe during the Middle Ages, while Sephardic Jews coalesced in the Iberian Peninsula and the Arab world. Between 40,000 and 100,000 Sephardic Jews were expelled from Spain in 1492 under the Alhambra decree and subsequently settled in North Africa, the Netherlands, Britain, France, Poland, and the Ottoman Empire, including major cities such as Istanbul, Selânik, and Bursa.
A 2006 study by Doron Behar and Karl Skorecki of the Technion and Ramban Medical Center in Haifa found that the vast majority of Ashkenazi Jews carry Middle Eastern ancestry. Nicholas Wade's 2010 autosomal study found that Ashkenazi and Sephardi Jews share roughly 30 percent European ancestry, with the remainder being Middle Eastern. Behar concluded that the most parsimonious explanation is common descent from ancient Hebrew and Israelite residents of the Levant.
Tefutzot, meaning scattered, is a modern Hebrew concept introduced in the 1930s by the Jewish-American Zionist academic Simon Rawidowicz. He argued to some degree for acceptance of the Jewish presence outside the Land of Israel as a modern reality and an inevitability, in contrast to the theologically negative galut tradition.