In īghāl, the intended proposition is substantially complete, but a final verbal addition—especially toward the end of a verse—provides a further meaningful refinement or intensity. In tadhyīl, an appended judgment embraces, reinforces, or generalizes the preceding point. Their common final position is not enough to merge the categories.
When the last word of a poetic line supplies a new aesthetic or semantic force, examine īghāl. When an additional independent statement confirms a prior proposition, examine tadhyīl. The key is the function of the addition, not simply where it appears.