spirit

In 1 Corinthians 14:15, what is the difference between praying «τῷ πνεύματι» versus «τῷ νοΐ»?

In 1 Cor. 14:15, it is written,

15 What is the outcome then? I will pray with the spirit and I will pray with the mind also; I will sing with the spirit and I will sing with the mind also. NASB

ΙΕʹ τί οὖν ἐστιν προσεύξομαι τῷ πνεύματι προσεύξομαι δὲ καὶ τῷ νοΐ ψαλῶ τῷ πνεύματι ψαλῶ δὲ καὶ τῷ νοΐ TR, 1550

What, if any, is the difference between praying «τῷ πνεύματι» (NASB: “with the spirit”) versus «τῷ νοΐ» (NASB: “with the mind”)? Or, is the apostle Paul using a parallelism thus equating the πνεῦμα with the νοῦς?