if I open an SVG file (in another app) and it shows several things, like this:
but when I open the very same file in Rhino you see many less things, like this:
all the names I don’t see listed as groups are just Object Names
for instance, I see IT-36 in the (other app’s) list of layers:
but I don’t see it in Rhino:
well… it’s the Rhino Object name of that curve 
so you’ll need to dig on both Object Names and Group Names if you want to find exactly the same stuff (also because the same object can be part of several different groups)
here there’s a C# script that tells you the group names:
I tried it here and it works perfectly
SVG_get_group_names.gh (12.8 KB)