How do تَمَارَضَ and مَرِضَ differ in the illustrated uses?

Seven Semantic Functions of Form VI (Tafāʿul): Reciprocity, Multiplicity, Pretence, Response, Equivalence, and Independent Uses

• The first feigns illness, the second states actual illness
• Both necessarily describe reciprocal action
• Both are passive
• The first is a noun and the second a particle