At Passover Rabbi’s ask, “Why is this night different?” At Easter, Gospel scholars read the fourth Evangelist and ask, “Why is this Gospel different?” It’s a complex question and I am admittedly not a Johannine specialist. But here are my preliminary thoughts:
D.A. Carson observes: “The thesis that John is literarily dependent on one or more of the Synoptics has not been demonstrated beyond reasonable doubt, but neither has the thesis that John is litearily independent of the Synoptics.” We simply have to develop new categories and frameworks for understanding the development of the Johannine tradition vis-à-vis the Synoptic tradition beyond dependent or independent because the relationship is more complex than this dichotomy allows. I suggest that we envisage the fluid movement and spasmodic inter-penetration of Synoptic and Johannine tradition across each other, recognize the independent nature of many of John’s sources, and envisage also John’s exposure to the Synoptic tradition through either a cursory reading or from observing an oral performance of a Synoptic-text. This accounts for the Fourth Gospel’s overall differentiation from the Synoptics in conjunction with his conscious adoption of the Marcan framework, the apparent interlocking traditions, and deliberate transposition of Synoptic themes. When that complex relationship is combined with the fourth Evangelist’s somewhat maverick approach in telling the Jesus-story encoded with symbolic meanings, amplifying a christology of sonship and messiahship, engaging in a midrashic interpretation of the sayings tradition, and richly interwoven with Jewish sapiential motifs, then I submit that we have a plausible explanation as to why the Gospel of John is what it is.
 Carson, Gospel according to John, 51 (italics original).