The number and identity of the women who went to the tomb differ. John 20:1 says that only Mary went to the tomb, while the synoptics have several women, but even they differ among themselves.
There was a literary convention typical of ancient bioi called literary spotlighting (where the author focuses on one character when there are more in the background), which seems to be occurring on Mary Magdalene in John 20:1. Raymond Brown notes in his commentary on John (John XIII-XXI, AYBC, 1970) that the Johannine author has the witnesses at the tomb "reduced to Magdalene" and that this "editorial reduction is an instance of the Johannine tendency to individualize for dramatic purposes" (p. 999). We can see literary spotlighting elsewhere in the Gospels. For example, in Luke 24:24 it says: "Some of those who were with us went to the tomb and found it just as the women had said; but they did not see him." Yet, we just learned in Luke 24:10-12 that only Peter went to the tomb! There seems to have been a spotlight shined on Peter there. We can also see literary spotlighting in John's own Gospel. In John 19:25, it says "standing by Jesus's cross" was "his mother, his mother's sister, Mary the wife of Clopas, and Mary Magdalene." Yet in the next sentence it also mentions the Beloved Disciple standing there!
So, while the author knew about further women at the tomb (cf. John 20:2), he chose to spotlight Mary. This does not bear on the origin of the core story. Spotlighting may be able to explain the difference among Mark Matthew and Luke, but it is possible that they weren't trying to be concise, or they had a different source which held a different number of women. Jewish scholar Geza Vermes (who holds to the historicity of the empty tomb) argues in favor of early tradition due to the differing identity and number of the women:
"The identity and number of the witnesses differ in the various Gospels, as does also their testimony. Yet it is clearly an early tradition. If the empty tomb story had been manufactured by the primitive Church to demonstrate the reality of the Resurrection of Jesus, one would have expected a uniform and foolproof account attributed to patently reliable witnesses."
(Geza Vermes, The Resurrection, 2008, p. 140)
The time at which the women reached the tomb differs: in Mark 16:2, it is “very early … after the sun had risen.” However in John 20:1, it is “early while it was still dark.”
While this is a contradiction at face value, Mark seems to depict the sun rising symbolically as a metaphor for Jesus' own rising, which means that we should prefer John's account.
Different number of angels at the tomb: Mark 16:5 and Matt. 28:2-4 mention one angel at the tomb, while Luke 24:4 and John 20:12 mention two.
Response: we learned about literary spotlighting above with regards to the amount of women at the tomb. Mark and Matthew may be doing such a thing on the angel making the announcement.
The posture of the angel(s) is different. In Matt. 28:2, he is “sitting” on the stone. In Mark 16:5, he is “sitting” on the right. In John 20:12, they are “sitting” where Jesus had once laid. But in Luke 24:4, the angels “stood beside”
A resolution also seems at hand here. The Greek word "epestēsan" typically means to appear or be present with no hint as to the posture taken. Luke employs this term in this way elsewhere in his Gospel (i.e Luke 2:9).
In the Gospel of Luke, Peter is the only male disciple to check on the empty tomb. John includes the Beloved Disciple.
This is also explained by literary spotlighting. In fact, Luke 24:22-24 proves that literary spotlighting is happening here. Luke 24:24 says:
Some of those who were with us went to the tomb and found it just as the women had said; but they did not see him.”
So Luke knew of further male disciples who went to the tomb, but spotlighted Peter. Thus, Luke's account agrees with John's.
In Mark, the women tell nothing to anybody, which was a huge problem for early Christians, as evidenced by the later additions to Mark in Mark 16:9-20. Matthew and Luke change Mark to have the women go straight to the disciples.
There seems to be a resolution at hand. In Mark 1:44, Jesus told a man whom he had just healed of leprosy:
“See that you say nothing to anyone. But go show yourself to the priest, and offer for your cleansing what Moses commanded, as a testimony to them.”
The command to say nothing to anyone is paired with the command for the man to go straight to show himself to the high priest and offer his cleansing as a testimony to them! The command is very similar in both cases. Thus, Mark 1:44 seems to be saying that the man should say nothing to anyone (except the high priest), whereas Mark 16:8 seems to be saying that the women should say nothing to anyone (except the disciples).
In Matthew, the women see Jesus on the way towards their intended goal of reaching the disciples. John has Jesus appear at the tomb
Granted. One of the Evangelists felt free to relocate the appearances of Jesus. I suspect Matthew did.
A major difference in the resurrection narratives pertains to where Jesus first appeared to a group of his male disciples. Matthew and Mark locate this appearance in Galilee, whereas Luke and John place it in Jerusalem. In fact, in Luke and John, the words of neither the angels nor Jesus at the tomb provide any hint of any appearance in Galilee and Luke explicitly bars any movement away from Jerusalem ("so stay here in the city until you have been clothed with power from on high").
Licona (2016, p. 177) observes,
In Luke 24:1–53, Jesus’ resurrection, all of his appearances, and his ascension to heaven are narrated as though having occurred on that Sunday. That Luke compressed the events in this manner is clear, since in the sequel to his Gospel, Luke says Jesus appeared to his disciples over a period of forty days before ascending to heaven (Acts 1:3–9).
"Given this, it is possible that the command to tarry (v. 49) was not given until after they had been in Galilee as instructed (Matt. 28:16) and came back to Jerusalem from there (Geisler and Howe 1997, p. 400). After all, Acts (which was written by the same author as Luke) told us there was a gap of 40 days, but this was not evident in Luke 24." (Andrew Loke, Investigating the Resurrection of Jesus Christ, 2020, p. 65)
Jesus shows his hands and side in John, whereas he shows his hands and feet in Luke
This is such a minor difference...
But granted.
With Judas dead, there were eleven main disciples. Thus Luke 24:33 can speak of Jesus’s first appearance to a group of his male disciples as including “the eleven and those with them.” However, John 20:19–24 tells us Thomas was absent during that event. Thus, only ten of the main disciples would have been present
Luke may have conflated the two appearances narratives