Does anyone have a detailed list of the difference in permissions between an administrator (employee with adminitrator role) and vendor center access with administrator role?

To my knowledge there is no difference. I quite often use a Vendor with Administrator role to access some client accounts. The only real consideration, particularly with customisations, is where a script may try to set an Employee field to the "current user". These scenarios may throw errors. When I build customisations that require "Created by" field as an example, I generally make the field type list/record:entity rather than employee. However some scenarios this is not possible, just something to be aware of.

I agree with you on this as I once encountered an error doing bundling before and cant proceed unless i login with a full access license user. I'm also wondering up to how many users can login with this role? In 1 prod acct with only 1 full access user license available i was able to use 2 vendor admin + 1 emp admin!? Thanks mate!

The full user count used is only checked when you edit/save employee records. You can technically add as many vendor/admins as you want, as the user count with access is not checked on Vendor save. Note, the downside is, if anyone needs to make a change of any sort on an employee record, save will be blocked if the used count is more than the available user count.

Appreciated your insightful note here mate 👍