﴿ يَلْبَسُونَ مِن سُندُسٍۢ وَإِسْتَبْرَقٍۢ مُّتَقَٰبِلِينَ ﴾

“wearing [garments] of silk and brocade, facing one another [in love].”

سُندُسٍ وَإِسْتَبْرَ‌قٍ... fine silk and thick silk.... - 44:53) Both the words refer to 'silk'. The word sundus refers to "fine silk" and the word istabraq refers to "thick silk".