Let's remember that in a memoir someone accounts the important events in his/her life. It can be about an specific theme or a certain part of life, in this case it is an event. Although we don't know which event they are talking about, we know how the information is presented.
As the memoir is personal and is written by the person that lived the event, it is going to be subjective, it will describe the things that people felt at that time as well as the problems they faced, all of this in the point of view of the author.
The newspaper article is going to be as objective as possible by just describing the events without taking anything in a personal way. Remeber it is trying to inform. The significant things are going to be determined by the importance they had in the outcome of this event. It will give a general description.
Imagine the event is a battle in Vietnam. The memoir is going to describe a soldier's point of view, it will describe if he was injuried, how he scaped or survived as well as the loss of close friends, etc. The newspaper article would describe the battle in general, counting the casualties and emphasizing the importance of that battle for the war in general.
