I feel that the plesk component should treat these two a bit more uniquely in a few places:
a ) id storage: should store the reseller id and not the webspace id of primary domain (more below)
b ) stats: for resellers it should really pull from the reseller info api and show things like accounts provisioned vs avail, total space used vs allocated
in recent versions 11.5/12, cant confirm previous, plesk allows the webspaces under a reseller directly to have a service plan or custom limits just like any other webspace. this makes it a misleading figure to show in blesta specially when it comes to space and such.