I do not own Gitar Rig Pro 6 version or any version, why am I offered Update or Upgrade options?
And if I pick the cheapest version 79$, do I really get Guitar Rig 7 Pro or something else that is not full version or pro version?
Since you seem to own the 'Collectors Edition', you should own Guitar Rig 6 Pro as it is included. Thus, the 'Update' option is correct.
What Monochrome wrote (descriptive : 'update' is from same product tier to newer of same product tier and 'upgrade' is from a lower product tier to a higher product tier of same generation or newer generation) (e.g. look at 'Compare page' for bundles !)