An ordinary adjective names a quality, whereas ism al-tafḍīl indicates a greater degree of that quality.
Word / formMeaning / explanation
كَبِيرٌbig, with no comparison necessarily expressed.
أَكْبَرُbigger or greater.
صَغِيرٌsmall.
أَصْغَرُsmaller.
In context the same morphological class can express a superlative (“greatest/smallest”). Translation therefore depends on whether a particular comparison or the highest degree is intended.