I want to apply a Gaussian blur to an image I imported into Illustrator. There are 2 tools from the menu, Effect-Blur-Gaussian Blur and Effect-SVG Filters-AI_GaussianBlur_4. I have applied both effects (using 4 as the radius for the normal blur). They appear almost the same, but not quite e.g. the SVG blur appears to be more intense and also blurs the edges of the image. What are the differences between these and which one is best for which purpose please?