What is Jesus saying here?  Is He making a distinction between Himself and God, the Father?  And if so, what type of distinction?

I think the difference Jesus is highlighting is relationship and understanding of God.  The Jews have believed in God, but they have not all known Him.  Jesus said, “No one knows the Father, but the Son, and who the Son reveals Him to” (Matt 11:27).  Without knowing the Son, they cannot know the Father…they can only know of the Father, which is what they do…and they know of Him as God alone.

They also cannot have an understanding of God’s true nature, apart from Jesus.  Jesus is the revelation of God’s true nature; His love, wisdom, power and truth.  So, without Jesus, we can’t enter into a personal relationship with God.  Jesus said, “I no longer call you servants.  I call you friends” (John 15:15).  Because of Jesus, we can have more than an awareness of God, we can have intimacy with Him!

Jesus had to make this distinction, so that they would know that IT IS NOT ENOUGH SIMPLY TO BELIEVE IN GOD.  It’s not enough to believe that God exists, or to know who God is, as the Hebrews do…

Read more at https://ufuomaee.blog/you-believe-in-god-believe-also-in-me/