How do the functions of اِسْتَرْقَعَ الثَّوْبُ and اِسْتَحْجَرَ الطِّينُ differ?

Ten Semantic Functions of Form X (Istifʿāl): Seeking, Suitability, Finding, Judging, Transformation, Adoption, Abbreviation, Response, Equivalence and Independent Use

• First suitability; second transformation
• Both are equivalence
• First seeking; second judgment
• First abbreviation; second finding