In Jainism and Hinduism the sound “Om / Aum” is written similarly in many Indian scripts, but its meaning and use are different.

Here is the difference in simple Jain terms:

1. Meaning of Om in Jainism

In Jain Dharma:

• Om (Aum) is a short form of the Navkar Mantra.
• It represents the five supreme beings (Panch-Parameṣṭhi):

- A – Arihant - A – Aşariri / Siddha - A – Acharya - U – Upadhyaya - M – Muni / Sadhu

So, when a Jain says or writes Om, it is like bowing to all five Parameṣṭhis together and remembering the Namokar Mantra and the Jain path of liberation. ( jainknowledge.com)

Both Digambar and Shvetambar accept this basic meaning of Om as connected with the Panch‑Parameṣṭhi and Navkar Mantra; minor differences are only in style of usage and surrounding rituals, not in core meaning. ( jainknowledge.com)

2. Meaning of Om in Hinduism (Jain view, in brief)

In Hindu traditions:

• Om is mainly seen as a cosmic sound linked to Brahman / creation, meditation on the universe, etc.
• It is not a shorthand for Arihant–Siddha–Acharya–Upadhyaya–Muni, and it is not connected to Navkar Mantra.

So, even if the symbol looks similar, the concept behind it is different.

3. Why Jains call it “Jain Om”

Because for Jains:

• Om = refuge in the five Parameṣṭhis + remembrance of Navkar Mantra
• It is used within Jain philosophy of ahimsa, karma, and moksha, not within Vedic / Brahman concept.

That is why many Jains clearly say:

• “Our Jain Om has a Jain meaning and is part of Jain Dharma, which is separate from Hinduism.” ( jainknowledge.com)

You can read a Jain explanation of this difference here