What is the difference in capacity per week between the processing plants at Laurel, Mississippi and Collins, Mississippi? 
{"Laurel, Mississippi": {"Market": "Big Bird", "Capacity Per Week  ": 650000, "Industry Bird Size": 8.95}, "Hammond, Louisiana": {"Market": "Big Bird", "Capacity Per Week  ": 650000, "Industry Bird Size": 8.95}, "Hazlehurst, Mississippi": {"Market": "Big Bird", "Capacity Per Week  ": 650000, "Industry Bird Size": 8.95}, "Collins, Mississippi": {"Market": "Big Bird", "Capacity Per Week  ": 1300000, "Industry Bird Size": 8.95}, "Waco, Texas": {"Market": "Big Bird", "Capacity Per Week  ": 1300000, "Industry Bird Size": 8.95}, "Palestine, Texas": {"Market": "Big Bird", "Capacity Per Week  ": 1300000, "Industry Bird Size": 8.95}, "St. Pauls, North Carolina": {"Market": "Big Bird", "Capacity Per Week  ": 1300000, "Industry Bird Size": 8.95}, "McComb, Mississippi": {"Market": "Chill-Pack Retail", "Capacity Per Week  ": 1300000, "Industry Bird Size": 6.52}, "Bryan, Texas": {"Market": "Chill-Pack Retail", "Capacity Per Week  ": 1300000, "Industry Bird Size": 6.52}, "Moultrie, Georgia": {"Market": "Chill-Pack Retail", "Capacity Per Week  ": 1300000, "Industry Bird Size": 6.52}, "Kinston, North Carolina": {"Market": "Chill-Pack Retail", "Capacity Per Week  ": 1300000, "Industry Bird Size": 6.52}, "Tyler, Texas": {"Market": "Chill-Pack Retail", "Capacity Per Week  ": 1300000, "Industry Bird Size": 6.52}}
capacity_collins = df["Collins, Mississippi"]["Capacity Per Week  "]
capacity_laurel = df["Laurel, Mississippi"]["Capacity Per Week  "]
answer = capacity_collins - capacity_laurel