What is the difference between indexed and crawling?

If a page has been crawled it means a search engine crawled it.
If a page has been indexed it means the search engine added it to its index. (Usually after crawling it.)

Crawling is the process of an engine requesting — and successfully downloading — a unique URL. Obstacles to crawling include no links to a URL, server downtime, robots exclusion, or using links (such as some JavaScript links) from which bots cannot find a valid URL.
Indexing is the result of successful crawling. I consider a URL to be indexed (by Google) when an info: or cache: query produces a result, signifying the URL's presence in the Google index. Obstacles to indexing can include duplication (the engine might decide to index only one version of content for which it finds many nearly identical URLs), unreliable server delivery (the engine may decide to not index a page that it can access during only one-third of its attempts), and so on.

Crawling- Google sends its spiders to your website..
Indexing- Google visited your website and has added you to its database..