In idiom, in metaphor and in demeanor they were were different poets. But both were voices of defiance whose metaphor was romanticism but whose subject were the harsh (talkh is a much more expressive word) realities of life. There are a number of reviews of the poetic legacies of both at ATP and I hope you will read them:
For now, let me only leave you with a video rendition of each… something to remember them with on this day (first video is of Parveen Shakir, and the second of Munir Niazi). Other great works by both are included in the posts mentioned above.