Let me try to keep the answer to this question to a minimum. Firstly, 3 of the 4 Gospels bear incredible similarity to one another, this has earned them the nicknames of the Synoptic Gospels. The Synoptic Gospels are Matthew, Mark and Luke. Obviously while they are similar there are differences, otherwise they'd just be copies of one another. Certain passages are in all 3 Synoptic Gospels and very few are in all 4.
Take the transfiguration for example: Matthew 17:1-8, Mark 9:2-8 and Luke 9:28-36 all record the same event and highlight different parts of it. Luke points out in verse 9:28 that they went to the mountain to pray. Matthew and Mark both omit this fact. After Jesus becomes transfigured Mark notes in 9:2 that Jesus' clothes become dazzling white as no one on earth could bleach them. Matthew and Luke do not mention that detail. And only Matthew notes that in 17:6-7 that when they heard the voice from Heaven that the disciples fell to the ground and were overcome with fear.
So how do we deal with details in the narratives of the gospels that differ?
Neither Mark or Luke record the disciples reaction to hearing the voice. Does that mean its a fabrication? Not necessarily.
Imagine you were standing on the corner of an intersection with some friends. You and your friends all witness a car speed through a red light and t-bone another car crossing on a green light. The police and ambulances arrive and ask you and your friends for details on the incident. One friend mentions that the person who ran the red light was an older woman who was distracted by texting on her phone. Another friend of yours reports that a lady was driving a blue ford mustang and wasn't paying attention. You notice that a mother stopped her child from crossing the crosswalk where the 45 year old woman would have ran them over. Which story is the correct one? Clearly, that is the wrong question to ask. Each person provides a different perspective on the same event, with certain details highlighted greater than others.
The same thing is true of the Gospels. In (almost?) all of the cases of differing details in the Gospels can be attributed to the fact that there was more than one witness. And just because there are differences does not mean there are contradictions. The same is the case with the Angels at the tomb. One gospel highlights that there was one, another that there is more than one. It is true that there is one but it is also true that there is more than one.