It really hinges on the chemical composition of the particular kava you're looking at, more than anything else: meaning, the different KL%, FK-B%, and other constituents, as they might be stated in a COA.
Single-cultivar kava will generally have more homogenous batch-by-batch COAs in comparison to blends (this will similarly apply to the more macroscopic "chemotypes," as they're called).
Speaking broadly, though, Hawaiian 'awa is generally said to be subtler, and sometimes "smoother" in its effects.