In the first three synoptic gospels, Bartholomew is simply listed as one of the apostles, and no other information about him is provided. He doesn’t speak any words and is simply a name on a list.
However, in the Gospel of John, Bartholomew is not featured at all, but the name “Nathanael” is mentioned.
According to the Catholic Encyclopedia, “The name (Bartholomaios) means “son of Talmai” (or Tholmai).” This means that Bartholomew is a last name, rather than a first name.
Furthermore, in the synoptic gospels, Bartholomew is always paired with Philip the apostle.
In the Gospel of John, it’s Nathanael who is mentioned along with Philip.
Philip found Nathanael and told him, “We have found the one about whom Moses wrote in the law, and also the prophets, Jesus son of Joseph, from Nazareth.”
John 1:45
This pairing has led many scriptures scholars to believe that Bartholomew and Nathanael are the same person, giving Bartholomew a bit more depth than simply another name in the list of apostles.