The Hellenists (Grecian Jews) most likely refers to Christians from a Jewish background who preferred to speak Greek.1 It is thought that a large number of Greek-speaking Jews had moved to Jerusalem in order to be buried near the city.2 Hebrews (Hebraic Jews) were Christians from a Jewish background who preferred to speak Aramaic. They would have been in the majority.3
1 Now in these days when the disciples were increasing in number, a complaint by the Hellenists arose against the Hebrews because their widows were being neglected in the daily distribution.