This is actually a really good question. And honestly, a hard one to answer.
During and throughout are pretty close in meaning but the slight differences can have a huge effect on English sentences.
Here are some examples:
"Throughout the 1960's the U.S faced many problems, socially, politically, and beyond"
"During the 1960's the U.S faced many problems, socially, politically, and beyond"
Here, the two words are pretty interchangeable. But this really only works with large chunks of time that you can talk about in general terms.
"During class, this kid started disturbing the students, so the teacher kicked him out."
"Throughout the class, the teacher had to keep reminding the student to keep quiet."
In this case, "during" refers to a specific moment in time that the speaker wishes to talk about. It basically means "There was this specific moment in time, during class, that the kid kept disturbing the students, so the teacher kicked him out." But without saying all of that and just saying "during."
"Throughout" in the second sentence is a more general term. As in, the thing that the speaker is talking about kept happening during class. (There's that use of "during" again)
Now there is one use of "throughout" that is really easy. I believe it functions as preposition in this case:
"Throughout the U.S, people mourned over the death of JFK"
This nuance of the English language is something that is best solved through interaction of the language. Just keep reading, listening, and conversing in English and I guarantee the uses of it will only become clearer.
Hopefully this was of some help to you!