"Type" or "variant": a recognized alternative rendering that stays inside the same identity. Most commonly heard of thekas — the many prakars of Teentaal keep its sixteen matras and clap pattern while varying fill and ornament for khayal, instrumental, or dance work.
Benares practice makes prakar development an art of its own, elaborating theka into near-compositional territory during accompaniment. The boundary matters: a prakar decorates the cycle without obscuring it; past that point it stops being theka.