Crawled – currently not indexed
The page was crawled by Google but not indexed. It may or may not be indexed in the future; no need to resubmit this URL for crawling.
Discovered – currently not indexed
The page was found by Google, but not crawled yet. Typically, Google wanted to crawl the URL but this was expected to overload the site; therefore Google rescheduled the crawl. This is why the last crawl date is empty on the report.