what's the difference between'over a period of time'and 'during a period of time'?

what's the difference between'over a period of time'and 'during a period of time'?

1.over a period of time：在一段时间内
Would you accept delivery spread over a period of time?
不知你们能否接受在一段时间里分批交货?
2.during a period of time：某段时间内(特指已发生过的某段时间)
During a period of time of developing,the Street basketball has become a kind of street culture of the world.
经过一段时间的发展,街头篮球已经成为一种面向世界的街头文化.