Holochain focuses on societal dimensions and qualitative relationships in forming multi-dimensional perspectives as consensus. It's more along the lines of human-to-human interaction, while IOTA is machine-to-machine economy. The Holochain team includes philosophers and humanities oriented people (social science and such), while IOTA is very much an engineering feat which tackles different problems altogether. They may in the future have some common ground of overlap here in there, but not fundamentally so.