How do isharah and iqtida most clearly differ?

Ibarat, Isharat, Dalalat and Iqtida of Text: Four Routes to Legal Meaning

• Both are only the primary purpose of discourse
• Isharah is always prohibition; iqtida is always analogy
• Isharah is an incidental implication; iqtida is an indispensable presupposition
• Neither has any relation to the text