@grahamperrin because web search sites are designed to figure out what might be useful to you based on a ton of different heuristics.

"exact word match" is rarely what people want by default, because the source material and the search itself can have misspelling, alternate spellings, and inflections.

in this case, my guess is that "net" and "bsd" get split out into separate search terms. at least part of that guess was based on seeing a link to some .NET stuff on the first page of results

fortunately, you can request an exact match by quoting the term: "netbsd" site:freebsd.org seems a lot closer to what you want?

@robn true, thanks.

Where <https://duckduckgo.com/?ia=web&t=h_&q=NetBSD+site%3Afreebsd.org> (without quoting) fails, <https://duckduckgo.com/?ia=web&t=h_&q=%22NetBSD%22+site%3Afreebsd.org> succeeds.

It's remarkable that Google Search succeeds without quoting.

Also, weird that 'Explaining FreeBSD' with the word 'NetBSD' disappears from the first page when I'm more exact about "NetBSD".

@grahamperrin it's really not that weird. different systems, different methods, different rules.

simplest answer for the differences I can imagine is to split terms first, then search vs search without splitting first, then splitting and retrying if you don't get good results

it won't be anything that simple, but that's a way to understand it

(fwiw simple term matching was like v1 of internet searching; hasn't been that simple since like 1995)