Presbyterian new age? Wow, I never in my life expected to hear staid old Presbyterians described as new age. Calvin & Knox must be turning over in their graves!!!.
Well, THE Presbyterian/Reformed distinctive is a focus on the sovereignty of God that extends to holding that God is the only agent of salvation. Presbyterians are more likely to speak of God's grace, while Baptists are more likely to speak of the believer's faith. (Of course, Presbyterians don't reject faith and Baptists don't reject grace. It is more a difference in emphasis than disagreement.)
But Presbyterians don't talk about "making a decision" for Christ, because in Presbyterian theology, God makes the decisions. Baptists (at least those I knew) speak of baptism as the believer's testimony or witness, a believer's act of faith and obedience. Presbyterians speak of baptism as a means of grace, as God receiving and welcoming the one baptized into the household of faith. So baptism is seen as a work and gift of God, not an act of the believer.
Along with that, the Baptist theology focuses primarily on the individual. Baptism is about God and the believer, each believer individually. Presbyterian theology focuses more on the community. Baptism is initiation into the Body of Christ, which is the Church.
I was very surprised when, after being baptized in a Baptist church, I was later contacted about becoming a member of the church. Coming from a United/Presbyterian background I had assumed that I was already a member by virtue of being baptized.
But basically, you are right. Beneath differences in practice and emphasis, most denominations (Protestant, Catholic & Orthodox) do hold to the same basic core beliefs. We may not all understand the Nicene Creed in quite the same way, but it remains a good summary of the core beliefs of the vast majority of Christians.