I spoke with @steveklabnik a couple nights ago and they informed that the terms 'crate' and 'package' are different concepts in the context of cargo. Someone in the #rust-tools channel on IRC just asked what the differences are. It might be worth clarifying this in the Frequently Asked Questions section (or maybe a different section?).

I'd be happy to write-up something for this, but I actually don't recall the distinctions from the conversation :)