What is the difference between logographic and phonetic signs in Sumerian writing?

In the Sumerian writing system, the distinction between logographic and phonetic signs lies in what the symbol represents.1

• Logographic signs: These are symbols that represent a specific meaning or concept, such as a numeral, a person's name, or a material object like cloth or grain. Early Sumerian writing was primarily logographic, using stylized pictures or conventionalized graphs to denote these concrete ideas.12
• Phonetic signs: These symbols represent a sound rather than a meaning. The adoption of the phonographic principle allowed the Sumerians to express abstract concepts, grammatical elements, and unpicturable words by using a sign to represent a syllable or sound.12

Because Sumerian words were largely monosyllabic, these phonetic signs typically denoted syllables. The script remained primarily logographic, utilizing phonetic signs only when necessary to clarify ambiguous graphs or to represent grammatical suffixes. Over time, this mixture of signs resulted in a word-syllabic script.21