How do you say “spread” in Italian? In Italian we say “spread” (lo spredde)

Italian newspapers and TV always mention the “spread” (read “lo spredde” since Italian words starting with “sp” need the article “lo” and not “il”.). I understand that “spread” measures a relation between the Italian BTP and the German Bund. Since I heard the word spread for the first time some months ago, this value has been in a range between 300 and 500, for example this article of the 12th August reports a spread of 431.  Can it be that the German Bund is 400 times more valuable than the Italian BTP? I do not understand properly but I understand that I do not understand exactly what the spread is as I tried to explain to a Spanish friend yesterday and I did not manage. She said she has not heard this concept in Spain.

Now I have not been living in Italy for at least 15 years. I have no formal education in economy. So it may be my fault. But why do Italian media have to use words and concepts I do not understand? How many Italian persons do understand “(lo spredde)” and the economic situation of the country?