No. Lord Mahavir and Gautam Buddha are not the same.

• Lord Mahavir ji is the 24th Tirthankar of Jain Dharma.
• Gautam Buddha is the founder of Buddhism.

They were different persons, lived in the same broad historical period, and taught different spiritual paths.

In Jain belief, Mahavir Swami is the fully liberated Tirthankar who revived and taught the Jain path of Ahimsa, Satya, Asteya, Brahmacharya, and Aparigraha.