1 Corinthians 12:10 (NKJV)
to another the working of miracles, to another prophecy, to another discerning of spirits, to another different kinds of tongues, to another the interpretation of tongues.
When most believers receive the baptism of the Holy Ghost, they receive the ability to speak in an unknown tongue, and most of the time, this ‘unknown tongue’ becomes their prayer language. There is a difference between ‘unknown tongue’ (as seen in 1 Corinthians 14:2), and ‘different kinds of tongues’ (as seen in 1 Cor 12:10).
While the purpose of speaking in ‘an unknown tongue’ is to talk to God (who does not need an interpreter) and to edify oneself (see 1 Corinthians 14:2,4), the purpose of the gift of ‘different kinds of tongues’ is to bring a message to people and edify them. All spiritual gifts are for the profit of all, not for personal edification (see 1 Cor 12:7). People would need tongues to be interpreted if it would profit them.
If you have been baptized in the Holy Spirit, that tongue you most likely speak is ‘an unknown tongue’ and not necessarily ‘diverse kinds of tongues’. You may have noticed that what you have been speaking is the same tongue or language that is not understood by anyone(see 1Cor 14:2), and there may be a lot of monotony to it. It is a tongue (an unknown tongue) and different from the gift of ‘tongues’ or ‘different kinds of tongues’.
The gift of ‘tongues’ or ‘different kinds of tongues’ helps those who have it to bring prophetic messages to people. It is equal to the gift of prophecy if interpreted (see 2 Cor 14:5). This should not be confused with speaking in ‘an unknown tongue’ or ‘a tongue’ which is used for praying to God. All do not have the spiritual gift of ‘different kinds of tongues’ (see 1 Corinthians 12:30), but all who have been baptized in the Holy Ghost would normally receive the ability to speak [to God] in ‘an unknown tongue’ (see Acts 10:46, Acts 19:6, Mark 16:17).
Go into today remembering that speaking in different kinds of tongues (1 Corinthians 12:10, 14:5) is different from speaking in an unknown tongue (1 Corinthians 14:2). The one is speaking unto men for their edification while the other is speaking unto God, and for self-edification.