No it's different. With edge mode there's no need to use smaller patches because we remove geometry outside of the spline at render time. The advantage is that you can use the same size patch for the whole area and still get nice clean edges. Actually it works by using the lowest Z Vertex of each of the item's individual elements to check if outside the scatter area. If true only the individual element is removed creating a clean edge, without slicing the geometry. Note that when using edge mode, an element is defined as a group of connected faces that share the same material ID, these are the same elements used by Forest Color.
With Forest Pack 5 which is currently in beta but out soon, if you want to combine Edge mode with the ability to swap segment's based on their distance from an edge you could use an Effect. In the following example I'm still using patches, one that's densely populated for the inside area and one that sparsely populated for edges.
Then, using the Edge Effect which I've attached to this post I can place the sparsely populated patches only at the edges. It uses the first item in the geometry list for the main areas and the second item for the edges. There's a single parameter to set the falloff distance. For more information on how to install effects in Forest Pack 5, check out the documentation here
This gives you grass that dies away as it reaches the edge instead of stopping immediately. This combination gives you the best of both worlds, efficient scattering of large patches plus the ability to swap segments at the edges.
I hope that helps, please let me know if there's anything else I can help with.