Premiere Elements 14 is one program.
Premiere Pro is a different program.
In either case, there is no difference between an upgrade version and a full version.
I have looked at the Amazon UK Premiere Elements 14, and it is very confusing what they are calling Standard and Upgrade for the discs and download that they are selling for this product. I cannot find a definition of Standard or Upgrade in that ad. And, I am not sure of that relationship to the Adobe's Full and Upgrade pricing only terms. Best check with Amazon UK Customer Service to get definition of its Standard and Upgrade.
There is only one Premiere Elements 14 that I know of whether it is labeled with Adobe's Full or Upgrade or Student and Teacher Version.
When you purchase from other than Adobe, you are subject to the pricing/pricing terminology, and return policy of the seller.
Adobe uses the "Full" pricing for when you cannot show proof of ownership of earlier version of the program, "Upgrade" when you can. Adobe's "Upgrade" is typically a lesser price than the "Full". But in the case of Amazon UK ad, it is giving a higher price to what it is calling Upgrade and a lower price to what is calling Regular. Definitely get input from Amazon UK customer service on this before purchase.