In my head granola is more about ethics and practicality, where boho is more of a broad style lane.
So granola (as worn by my family) would tend to be a fair-trade cross-body pouch with crocs or clogs or tevas and maybe a fleece pullover jacket. Could be peasant skirts, jeans or leggings, or vegetable dyed jersey skirts from yoga gear companies. Environmental tee shirts, you get the picture.
boho could be more festival wear on younger people, or Santa Fe/desert/beach wear on people of all ages. Or have strong retro late 60's-70's elements or global village elements. More about an overall romanticized look even though it's quite a large category.
I could be totally off though, so grain of salt.
ETA: what lisap said