TL;DR
There is no real difference: web crawler, web spider, and spiderbot are three names for the same thing, a program that systematically follows links to discover and download pages. Spider is the older, more informal term; crawler is the standard one today. Both describe the traversal loop, not data extraction.
Same Thing, Different Eras
The word "spider" comes from the early web metaphor of a program moving across the "web" of linked pages. It was common in the 1990s and early 2000s and survives in tool names (Scrapy calls its crawl units "spiders"). "Crawler" won out as the neutral technical term, and search engines describe their bots as crawlers (Googlebot, Bingbot).
When someone says spider, spiderbot, or crawler, assume they mean the same link-following program unless context says otherwise.
Where Real Distinctions Live
The naming is a synonym, but adjacent terms do carry real differences worth keeping straight:
- Crawler vs scraper. This one is substantive: crawling discovers URLs, scraping extracts data. See crawling vs scraping.
- Crawler vs bot. "Bot" is broader; every crawler is a bot, but many bots (chatbots, trading bots) never crawl.
- Spider in framework terms. In Scrapy specifically, a "spider" is a class you define per site, a code-level unit, not a different kind of program.
Why the Confusion Persists
Documentation, job posts, and vendor pages mix the terms freely, and older tutorials lean on "spider" while newer ones say "crawler." Treat them as interchangeable and focus on the actual behavior described: is the tool discovering pages (crawling) or reading them (scraping)? That distinction matters; the crawler-versus-spider label does not.
Key Takeaways
- Web crawler, web spider, and spiderbot are synonyms for the same link-following program.
- "Spider" is older and informal; "crawler" is the modern standard.
- The distinction that actually matters is crawler (discovery) vs scraper (extraction).
How ScrapeGraphAI Handles This
Whatever you call it, ScrapeGraphAI's crawl endpoint handles the traversal and extracts data from each page it reaches, combining the spider's job of finding pages with the scraper's job of reading them.