No offense but with all the latest tech you should easily know about basics of PSUs. Look up the specs read them, they are self explanatory.

The 80+ ratings refer to efficiency. See this chart for reference

The reason for price differences is quality of components. BUT that doesn't mean that lower efficiency means bad components.
A lot of people buy the Gold level psu's (especially EVGA brand) because they are a good value. Higher efficiency means that it will run a little cooler and normally a little quieter.
Gold is especially reliable with EVGA psu's. So the one your considering should serve you well. It has a 10-year warranty with registration which is excellent.
In 10 years you'll probably need your own portable nuclear reactor anyway
 
Most importantly the 1300W rating is plenty for your equipment. No worries there.
There was a concern about transient power spikes on high end Nvidia cards but the 4090 so far are proving to be not as bad as the 3090 was according to Gamers Nexus.
Even so your 1300W GT should handle even those issues.
 
Here's EVGA's announcement info on the GT series
https://www.evga.com/articles/01406/evga-gt-psu/
 

Absolutely the answers I was looking for, thank you very much for taking the time to help out.  Now I have enough info to further educate myself. never stop learning.....
 
 I know that an EVGA 1300 would be plenty of power across the board as they all seem to have the same 108.3A total on the 12volt, but that difference in the gold and plat really threw me for a loop, BUT I just spotted in the EVGA store that all of the PSU'sare on sale!! So I have decided to go with this one: EVGA - Products - EVGA SuperNOVA 1300 P+, 80+ PLATINUM 1300W, Fully Modular, 10 Year Warranty, Includes FREE Power On Self Tester, Power Supply 220-PP-1300-X1 - 220-PP-1300-X1
 
 I could get the Gold 1300  GT today at my local store and I have cash saved up for it so that was also a factor, but this one is just a tad bit more WITH free shipping and I would feel comfortable getting the best I can afford for this build. My last EVGA Plat PSU has been a flawless workhorse for many years now.  I just have to wait a week or so to receive it.
 
 And I don't mind using the pigtail/style adaptor, for now, I have had this motherboard for a few months and I finally got my the new case I wanted for it, so it's time to start assembly. At the moment my wife and I share a PC because her old AM2 Vista rig sucks, she hates it!! She wants this one, she likes windows 11 now after resisting changing from Vista for years (she likes the email app..lol), and if we're buying a new PC we are building it!!
 
thanks again everyone

I ran a 1300GT Gold... first one fried... now rma'ed it and it the space of 3 months my new 1300GT turned off never start again. I am mad beyond belief. I WILL NOT BUY eVGA again!.. those PSU are junk