Crawling is the process of Googlebot. Crawler scans the content/Images of the website and sends it to the spider for indexing your content in the Google search engine. It is a process of indexing your content. The indexing means that your website content has indexed into the Google search engines.
Crawling is a process that is done by search engine bots to discover publicly available web pages. Indexing means when search engine bots crawl the web pages and save a copy of all information on index servers and search engines show the relevant results on search engine when a user performs a search query.