• Acharya: In Jainism, an Acharya is the highest spiritual and administrative head of a Jain monastic order. The Acharya is responsible for guiding the order, interpreting canonical teachings, preaching, and performing ordinations (diksha) of monks and nuns. The Acharya also issues rules and resolutions for the order and oversees the education and conduct of its monks and nuns. There are differences in practice and titles between Digambar and Shwetambar traditions, but the core role is the same: the supreme teacher and leader of the order.

• Upadhaya: An Upadhaya is a senior, learned teacher within the Jain community who is authorized to teach the scriptures and guide students—often on the path for both monks and lay followers. In many lineages, an Upadhaya assists the Acharya by delivering sermons, teaching Jain alter-practice, and supervising the study of canonical texts. The Upadhaya is typically a respected instructor and mentor, and in some contexts may be involved in formal initiation or instruction of novices, under the authority of the Acharya.

• Relationship and differences: Generally, the Acharya is the highest authority in a Jain order, while Upadhaya is a senior teacher who supports and carries out theological and educational duties under the Acharya. The exact duties and status of Acharya and Upadhaya can vary between Digambar and Shwetambar communities, with each tradition having its own conventions about ordination, teaching roles, and lineage.

If you’d like, I can share more details on how these titles are practiced in a specific Jain tradition (Digambar or Shwetambar), or point you to authentic Jain texts or commentaries that discuss their roles.