Usually the official transcript, since it lists the courses and often names the programme stream, supported where necessary by a registrar's letter. The parchment alone frequently states only the degree name, which is why it is rarely sufficient on its own for this particular purpose.
Pair the parchment with the transcript
Provide the two together so the degree name and the coursework can be read against each other. If the transcript still does not name the specialization, ask the registrar for a short letter confirming the stream and the requirements completed. A programme calendar page adds context but is not an individual record, so it supports rather than replaces institutional confirmation of what this particular student completed.
Inconsistency across an agency contract, a client statement, and a support letter is a common source of difficulty, because each was drafted for a different purpose. Rather than listing responsibilities as headings, ask for sentences describing the work: which assessments are performed, which patient populations, what supervision consists of and how often. Build a short support letter or employer statement around the facts the commercial agreement leaves out: the US recipient, work location, temporary period, remuneration, supervision, and specific deliverables. Citizenship proof, the licence, the certification and translations are then checked against what that letter claims.