ID based on previous guidance from @rfoster as follows -
"... the lines across the snout and under the eye. In the ornate cowfish they are generally more tightly packed and, importantly, they run obliquely downwards from the snout. Shaw’s usually has fewer, wider lines between eye and mouth that tend to be more or less horizontal.
If you can examine the caudal peduncle (tail base) the degree of ‘armour’ is a good guide – ornata has its tail base almost enclosed by bony plates whereas these plates are rudimentary in aurita (Shaw’s)."