What is the difference between LCP and INP?
LCP measures when the biggest visible element finishes rendering (loading). INP measures how fast the page responds when someone taps or clicks (responsiveness). A store can pass one and fail the other.
Largest Contentful Paint is about what shoppers see: the moment the hero or product image finishes loading. Interaction to Next Paint is about what shoppers feel: the delay between a tap on 'add to cart' and the page visibly responding.
Different problems cause each. LCP failures are usually image weight, format, or server slowness. INP failures are usually JavaScript - especially third-party scripts - blocking the main thread. Diagnose them separately; fixing images will not help a page whose main thread is saturated.