They are same tongues is for praising God, in Acts 2 they were praising God and people were hearing their own languages. There is 2 miracles going on here. If you have 100+ people all speaking in different languages you wouldn't be able to make anything out. They were extolling the mighty deeds of God to Him and people were given the gift of being able to understand in their native languages. Tongues is to Him and prophesy is to the people according to 1 Co 14. When the Gentiles spoke in tongues we see the same thing, they are praising God.