Why is the price different from steam
Namely for an introduction price of a newly released indie game. Indie Devs oft have a soft -10 to -30 % off the MSRP to allow interested gamers to hop onto it and support the dev with a bit of savings.
Ichi.io oft have their own sales by the developers discretion may the be bundles and what not. Moreover, Itch.io focuses on indie devs having the near to full purchases from their customers. Which at release it will typically be at regular MSRP instead of of the introduction pricing that steam has.