Before revision:  This points out that economic systems behave differently at different scales: while countries tend to diversify their production - potentially exporting a large number of different products - firms specialize in exporting (substantially very limited) baskets of basically homogeneous products.
After revision:  This points out that economic systems behave differently at different scales: while countries tend to diversify their production - potentially exporting a large number of different products-- firms specialize in exporting (substantially very limited) baskets of basically homogeneous products.