Why do botanists use division while zoologists use phylum for equivalent ranks?

In biological taxonomy, the use of different terms for equivalent ranks—division in botany and phylum in zoology—is primarily a result of historical tradition rather than a functional or biological necessity.1

Each major group of organisms has its own unique taxonomic history, and these established naming conventions have been preserved over time. Because there are no explicit, universal taxonomic characters that define a specific rank, the classification of organisms relies on a general consensus among practicing taxonomists within their respective fields.1

This divergence in terminology can lead to awkward situations, particularly when classifying organisms like the Protista, which are of interest to both botanists and zoologists. In such cases, the term used typically follows the prevailing practice of the field: phylum is generally used for animal-like protozoa, while division is used for more plantlike protistan groups. Ultimately, these naming differences reflect the independent development of international codes of nomenclature for different biological disciplines.234