In simple language meaning of orchestra is presentation of different types of instrument players coming together on the same platform and performing in same raga & rhythm. The performance may by with or without vocalists. Every performer plays his instrument with accuracy by following certain rules of music. Their coordination and collective activity creates a wonderful music.
In devotional music there are different categories like bhajan, kirtan, mata ki chowki, etc. Devotional songs are normally sung in group in which there is a lead singer who sings the first line or stanza and its followed by the chorus. Devotional songs or bhajans are based on themes dedicated to god.
Traditional instruments are generally used in this type of orchestra like Harmonium, Tanpura, Flute, Tabla, Jhanj, Percussion etc. Devotional music is normally used to praise the God.