They're not interchangeable, but "reference" has so many meanings that it covers both.
An "attest" is a written statement or testimony, which attests to a person's qualities and qualifications. It could be a favourable reference from your previous boss or co-worker, but also covers many official certificates; birth certificates, vaccination certificates, etc.
A "referanse", in the context of applying for a job, is either a person who will vouch for you abilities, or the reference to such a person. The act of referring something, or referring someone to someone, is also a referanse, as are citations/references in academical works.