According to the SVG 1.1 spec, the two paths in the attached test case should share the same pathSegList, normalizedPathSegList and d attributes (with themselves and each other). Instead, the DOM-generated path doesn't have the d attribute and neither has a normalizedPathSegList.
Created attachment 63279 [details] Test case showing missing path seg list properties/attributes.
The test case seems to produce identical output for both cases in Safari 15.5+.