The HongDian 525 is substantially heftier than the no-name clone of apparently the same design.
The metal grip section on the HongDian 525 is brushed; the metal grip section on the no-name clone has a matt finish.
The HongDian 525's nib can be removed by way of unscrewing the nib unit (nib, feed, and the collar that goes around them), whereas the plastic collar around the nib and feed in the no-name clone is either glued in or jammed into the metal grip scection, and cannot be removed. A convex rim of the collar protrudes slightly above the rim of the metal grip section on the no-name clone.
The exterior finish on the HongDian 525's body has more of a velvety texture, feels grippier and nicer to me subjectively, and reflects less light. The finish on the no-name clone's pen body is smoother, and has more of a metallic sheen, even though it is still matt rather than glossy.
There is a discrepancy in the colours of the cap and the barrel of the no-name clone.
The clip on the HongDian 525 is slightly longer than on the no-name clone.