This document discusses models for distinguishing between languages and dialects. It examines the hierarchical family tree model and notes limitations with this approach. Specifically, isoglosses representing different linguistic features do not always align and can intersect, contradicting the assumption in the family tree model that isoglosses should never cross. The document concludes that isoglosses on their own are not sufficient to reliably delimit linguistic varieties, calling into question how to distinguish varieties if not by isoglosses alone.