Born again and baptism of the Spirit
1 Corinthians 12: 3 says: “no one can say that Jesus is Lord except by the Holy Spirit.” That means the born again experience and salvation is a work of the Holy Spirit that happens in a human being. That also means that all born again believers have the Spirit in a measure.
But the baptism of the Holy Spirit is a different experience. It happens to those who believe in Jesus Christ and are saved by faith. It refers primarily to the out pouring of the Holy Spirit on the day of Pentecost on the apostles and many others who were gathered in the Upper Room. The Book of Acts goes on to narrate more incidents of the baptism of the Spirit on believers. So baptism of the Holy Spirit is what happened on the day of Pentecost, the early church and to the church today.