Short answer:

• The Hindu Om and the Jain Om look similar, but in Jainism the symbol has a specific, different meaning and use. In Jain practice, Om (Aum) is a condensed reference to the five parameshthis (Arihanta, Siddha, Acharya, Upadhyaya, Muni) and is often used as a mnemonic for taking refuge in them, especially together with the Navkar Mantra. In Hinduism, Om is a sacred sound or syllable connected to Brahman and the cosmic creation, not a shorthand for the five Jain beings. This is why many Jains treat Jain Om as distinct in meaning from the Hindu Om. ( jainknowledge.com)

More detail (in simple terms):

• Jain Om = AAAUM (the initials of five sacred Jain beings) or a compact form of Navkar Mantra’s refuges. It is used to remind the practitioner of Ahimsa, the Ratnatraya (right faith, right knowledge, right conduct), and the path to moksha. In many Jain traditions, Om is a symbolic shorthand for bowing to Arihants, Siddhas, Acharyas, Upadhyayas, and Sadhus. ( jainknowledge.com)
• Hindu Om = a broader spiritual sound associated with the ultimate reality, Brahman, and is not tied to the five Jain beings. Its significance is rooted in Hindu cosmology and Vedantic thought, rather than the Jain Navkar framework. ( en.wikipedia.org)

Tradition differences to note:

• Digambar and Śvetāmbara traditions both use Om in Jain practice as a symbol or shorthand for honoring the five parameshthis; the exact stylistic representation may vary, but the underlying Jain meaning remains focused on refuge and the path to liberation. ( jainknowledge.com)

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