Answer

The correct terms are usually Tirthankar, Kevalbhagwan (more commonly Kevali Bhagwan or Arihant), and Siddha Bhagwan.

Main difference:

• Tirthankar = an omniscient soul who establishes the Jain Tirtha and shows the path of liberation to others.
• Kevalbhagwan / Kevali Bhagwan = an omniscient soul who has attained Keval Gyan, but is not necessarily a Tirthankar.
• Siddha Bhagwan = a soul that has completely liberated from all karma and is now in the state of final freedom.

Explanation

1) Tirthankar

A Tirthankar is a very special soul in Jainism.

• Attains Keval Gyan
• Preaches the Jain path
• Establishes the Chaturvidh Sangh: monks, nuns, laymen, and laywomen
• Revives the Jain religion in that time cycle

So, every Tirthankar is a Kevali, but every Kevali is not a Tirthankar.

2) Kevalbhagwan / Kevali Bhagwan

This means a soul that has attained Keval Gyan — complete omniscience.

• The soul is free from ignorance
• It knows all substances and truths directly
• It may still have a body for the rest of that life
• If it is not a Tirthankar, it is still a fully enlightened soul, but without the special role of founding the Tirtha

In simple words:

• Tirthankar = Keval Gyan + special role of teaching and establishing the Tirtha
• Kevali Bhagwan = Keval Gyan, but not necessarily a Tirthankar

3) Siddha Bhagwan

A Siddha is a soul that has become fully liberated.

• All karmas are destroyed
• No body remains after the final life ends
• No birth, death, hunger, pain, or attachment
• Resides forever in the state of Siddhashila

A Siddha is the highest state of the soul in Jainism.

Spiritual Understanding

The progression is generally understood like this:

1. Arihant / Kevali

The soul is omniscient and still in a body.

1. Tirthankar

A special Arihant who also establishes the Jain path for the world.

1. Siddha

After the body ends, the soul becomes completely free forever.

Takeaway

• Tirthankar = omniscient teacher and path-maker
• Kevalbhagwan = omniscient soul, not always a Tirthankar
• Siddha Bhagwan = fully liberated soul beyond all worldly existence

If you want, I can also give this in a very simple table form.