Load time is a vague metric that doesn’t describe the user expierence when a website loads, which is why we don’t use it anymore.
FCP is first contentful paint, the first visual element that appears on a page.
LCP is the moment the largest element on that page finishes loading.
An ideal FCP time would be 1.5s, less then that isn’t common, becuase of DNS lookup times and such
For when the LCP element is an image, usually 4-5s would be considered good for an image that is twice the size of it’s container element(for best viewing on 2.0 dpi screens).