i'm pretty sure the method mentioned in the article finds single topic assignments where LDA finds mixtures of topics. hierarchical in LDA refers to the stacke

i'm pretty sure the method mentioned in the article finds single topic assignments where LDA finds mixtures of topics. hierarchical in LDA refers to the stacked multinomial nature of the model over word counts, documents and topics. hierarchical in bertopic means assuming and finding a hierarchical relationship between the topics themselves at cluster time. they use the same word, but appear very different things, at least to me.