Majhi, spoken in Amritsar, Tarn Taran, Gurdaspur and across the line in Lahore and Sheikhupura, is the basis of standard written Punjabi. What is taught as Punjabi is Majhi.
Malwai is spoken south of the Sutlej, in Ludhiana, Bathinda, Sangrur and the rest of the Malwa, and is the dialect of most Punjabi popular music.
Doabi is spoken between the Beas and the Sutlej, in Jalandhar and Hoshiarpur, and is the dialect of most of the Britain and Canada diaspora.
Powadhi is spoken around Rupnagar, Mohali, Fatehgarh Sahib and into Haryana. Pothohari, Hindko and the western dialects are now almost entirely in Pakistan.
The differences are of vocabulary, of verb endings and of intonation, and a Punjabi can usually place another Punjabi's district within a sentence or two.
Nobody has produced a modern dialect atlas of Punjabi. The last serious survey work on Punjabi dialects across the whole language area was done before 1947 and the language area has been divided ever since.
Majhi, Malwai, Doabi and Powadhi on this side, and Pothohari, Saraiki, Hindko, Multani and the bar dialects on the other, cover a range wide enough that the ends are barely mutually intelligible.
The written standard is Majhi, which means most Punjabi speakers in India write a dialect that is not the one they speak.
The dialect atlas of the region does not exist. Nobody has mapped the isoglosses across the two countries and no institution on either side is doing it.