How is a Sikh person different from a Punjabi person ?
A Punjabi person is someone who comes from the Punjab region (India or Pakistan) or speaks Punjabi language or follows Punjabi culture (food, music, traditions).
Punjabi people can follow any religion, like Sikh, Hindu, Christian, & Muslim. So, you can be Punjabi Sikh, Punjabi Hindu, Punjabi Christian, & Punjabi Muslim.
A Sikh person is someone who follows Sikhism, a religion founded by Guru Nanak Dev Ji. Believes in one God, equality, seva (service), and honesty. They may keep the 5Ks (Kesh, Kara, Kanga, Kachera, Kirpan).
Sikhs can be from any ethnic background, not only Punjab. But most common is Punjabi Sikhs. Sikhs are also found in UP, Maharashtra, Bihar (specially in India). Internationally Sikhs are everywhere, but the main population is in the UK, Canada, and US.