Changes include:

• Crucial reveals about the IRIS' s project's goal were moved from CH4 to CH2
• Certain lore details\explanations have been changed\simplified\moved to NG+
• New intro and CH3's dialogue important for better understanding of the timeline and the main plot.
• A brand new ending with better transition, including three new cutscenes and two maps.
• Gem's backstory simplified and partially moved to NG+
• Minor changes (difficulty, items placement, etc)