Salwar-kameez :
Is an outfit better known, more convenient, and brought to Kashmir and Punjab (regions with predominantly Muslim and Sikh).
The salwar is a baggy pants that attaches to the waist and ankles tightens. It is worn with a short or long tunic called kameez.

Churidar : 

Is another outfit that looks like Salwar but tighter. It is worn with a long tunic with or without collar called Kurta (for women hindous).

Lengha : 

More specifically brought to the West of India. This is an outfit consisting of a long skirt and a long tunic or a choli. In other parts of India the lengha is worn only on special occasions (can be worn by women indhues, Muslim, Jain and Sikh).