Answer:

By Indian I assume you mean the subcontinent of India. Similarities? Both make use of scales and modes that aren't diatonic in the Western sense. Both have roots in very old musical traditions. There is an emphasis on both that singing employs passion and a certain amount of improvisation.Both use accompaniments on a few instruments for their sound (Indian being the sitar, and the guitar for Spanish. )

Differences: Indian music employs and uses the 1/4 tone as a distinct legitimate pitch,. Where Spanish music makes use of some scales and modes deriving from their Moorish Muslim and gypsy roots, but fit into Western harmonic expressions.