What is the primary distinction between tashrīʿ and sajʿ?

Qalb, Tashrīʿ and Luzūm Mā Lā Yalzam: Completing the Verbal Ornaments

• Sajʿ is only poetry and tashrīʿ only prose
• Tashrīʿ gives two valid endings to one verse; sajʿ relates prose endings
• Tashrīʿ only compares meanings
• Sajʿ always reverses letters