We have the first fruits of the Spirit. We still groan inwardly as we wait for the full adoption, the redemption of our bodies (Rom 8:23).
First fruits are the first part of the harvest. Getting them guarantees the rest is coming.
The Spirit now is a foretaste of what is still to be given.
Ephesians 1:13-14 uses a different picture for the same idea. We are sealed with the Holy Spirit. He is the guarantee, a down payment, of our inheritance.
Fruit of the Spirit in Galatians 5 is a separate idea. That is about what the Spirit produces in a life.