I can think of one reason why the book of John is different than the others. John is someone special...
Now there was leaning on Jesus' bosom one of his disciples, whom Jesus loved. 13:23
When Jesus therefore saw his mother, and the disciple standing by, whom he loved, he saith unto his mother, Woman, behold thy son! 19:26
Then she runneth, and cometh to Simon Peter, and to the other disciple, whom Jesus loved, and saith unto them, They have taken away the Lord out of the sepulchre, and we know not where they have laid him. 20:2
Who is that disciple?
This is the disciple which testifieth of these things, and wrote these things: and we know that his testimony is true. 21:24
It's John. Among all the apostles, only John received that special attention. No wonder he would have a different view on things. No wonder he was able to write the book of Revelation.