Heh? That post says its show-me-where-foo-is-defined functionality is broken sometimes, but it doesn't show it (and presumably they never filed a bug upstream either). I compared the two at some point last year, and they did produce slightly different results, with cscope being slightly more correct about something, but I don't recall exactly; they were VERY similar.
But GNU Global is being maintained, while cscope was abandoned. With GNU Global, you can actually update your database without recreating your tag database again. This is very useful for editor integration when you finish editing a file and save it.
1. Where is symbol "foo" mentioned? 2. Where is function "foo" called? 3. What other functions does function "foo" call?
GNU global can do #1, but not #2 or #3.