Using PostgreSQL and jsonb with Ruby on Rails – Nando Vieira

hstore columns don’t allow a nested structure; they also store all values as strings, which will require type coercion on both database and application layers. With json/jsonb columns you don’t have this problem; numbers (integers/float), booleans, arrays, strings and nulls are accepted, and you can even nest structures in any way you want.

Source: Using PostgreSQL and jsonb with Ruby on Rails – Nando Vieira