At the time of partition both India and Pakistan were agriculture driven, there is no notable industry in whole subcontinent. While West Pakistan had a lot better irrigation system than India, East Pakistan enjoyed having almost all her land being arable. Also Pakistan had much lesser population than India at the time of partition, means less empty belly to take care for; so Pakistan was supposed to do better than India, and indeed it better in first few decades as mentioned by a poster before.
But we also need to consider the people of East Pakistan when discussing India-Pakistan economic situation of pre-Bangladesh era. Although East Pakistan contributed a large portion of total Pakistan GDP, the Pakistanis of East-Pakistan weren't an example of rapid economic development.
We also should take into consider that after opening up economy, India always did better than Pakistan which was never a closed economy to begin with.
^Above picture invalidates some myths about Pakistan Economy and WOT. Considering WOT started in Pakistan in it'd full form only after 2006(the suicide blasts and all the mess), Pakistan wasn't doing great pre-WOT as well.