An apostille and a background check answer two different questions. One asks what your criminal history is; the other asks whether the document saying so is authentic. That is why applicants are so often asked for both, and why neither substitutes for the other.
Why Some Countries Require Both
The background check answers what your record contains. The apostille answers whether the document is genuine. Neither replaces the other, which is why you are asked for both.
Does Every FBI Check Need an Apostille?
No single office can authenticate every American document — the correct authority depends on who issued the underlying one. Where a federal apostille applies, and the pathway it follows.
Apostille vs Embassy Legalization
Some destinations require legalization rather than an apostille, and requirements change. Different document types from the same applicant can follow different paths.