Solve the following sql problem:
Among the competitors with age ranges 24 and below, calculate the difference between the number of competitors who weighed greater than 70 kg and competitors who weighted less than 70 kg.

Schema:
SCHEMA:
- Table: city
  - Column: id
    - Samples: [1, 2, 3, 4, 5]
  - Column: city_name
    - Samples: [Barcelona, London, Antwerpen, Paris, Calgary]
- Table: games
  - Column: id
    - Samples: [1, 2, 3, 4, 5]
  - Column: games_year
    - Samples: [1992, 2012, 1920, 1900, 1988]
  - Column: games_name
    - Samples: [1992 Summer, 2012 Summer, 1920 Summer, 1900 Summer, 1988 Winter]
  - Column: season
    - Samples: [Summer, Summer, Summer, Summer, Winter]
- Table: games_city
  - Column: games_id
    - Samples: [1, 2, 3, 4, 5]
  - Column: city_id
    - Samples: [1, 2, 3, 4, 5]
- Table: medal
  - Column: id
    - Samples: [1, 2, 3, 4]
  - Column: medal_name
    - Samples: [Gold, Silver, Bronze, NA]
- Table: noc_region
  - Column: id
    - Samples: [1, 2, 3, 4, 5]
  - Column: noc
    - Samples: [AFG, AHO, ALB, ALG, AND]
  - Column: region_name
    - Samples: [Afghanistan, Netherlands Antilles, Albania, Algeria, Andorra]
- Table: person
  - Column: id
    - Samples: [1, 2, 3, 4, 5]
  - Column: full_name
    - Samples: [A Dijiang, A Lamusi, Gunnar Nielsen Aaby, Edgar Lindenau Aabye, Christine Jacoba Aaftink]
  - Column: gender
    - Samples: [M, M, M, M, F]
  - Column: height
    - Samples: [180, 170, 0, 0, 185]
  - Column: weight
    - Samples: [80, 60, 0, 0, 82]
- Table: games_competitor
  - Column: id
    - Samples: [1, 2, 3, 4, 5]
  - Column: games_id
    - Samples: [1, 2, 3, 4, 5]
  - Column: person_id
    - Samples: [1, 2, 3, 4, 5]
  - Column: age
    - Samples: [24, 23, 24, 34, 21]
- Table: person_region
  - Column: person_id
    - Samples: [1, 2, 3, 4, 5]
  - Column: region_id
    - Samples: [42, 42, 56, 56, 146]
- Table: sport
  - Column: id
    - Samples: [1, 2, 3, 4, 5]
  - Column: sport_name
    - Samples: [Aeronautics, Alpine Skiing, Alpinism, Archery, Art Competitions]
- Table: event
  - Column: id
    - Samples: [1, 2, 3, 4, 5]
  - Column: sport_id
    - Samples: [9, 33, 25, 62, 54]
  - Column: event_name
    - Samples: [Basketball Men's Basketball, Judo Men's Extra-Lightweight, Football Men's Football, Tug-Of-War Men's Tug-Of-War, Speed Skating Women's 500 metres]
- Table: competitor_event
  - Column: event_id
    - Samples: [1, 2, 3, 4, 5]
  - Column: competitor_id
    - Samples: [1, 2, 3, 4, 5]
  - Column: medal_id
    - Samples: [4, 4, 4, 1, 4]

SELECT COUNT(CASE WHEN T1.weight > 70 THEN 1 ELSE NULL END) - COUNT(CASE WHEN T1.weight < 70 THEN 1 ELSE NULL END) FROM person AS T1 INNER JOIN games_competitor AS T2 ON T1.id = T2.person_id WHERE T2.age < 24