Answer:
Jesus is talking about the Salvation experience where we are “born again” spiritually.
The Baptism is a further immersion into the fullness of the Spirit, but one could certainly get to Heaven without it. After all, the disciples were born again after Jesus resurrection and when He breathed on them. However, Jesus told them to wait in Jerusalem for the Holy Spirit (baptism) so they would be empowered for ministry.
I hope this helps explain the difference.
See also: Do you have to be baptized in the Holy Spirit to go to heaven?