"Plus" in Quick hot air product numbers? (957DW+ vs 957DW, etc)

[Dave8266]

"Quick" question, sorry for the pun.   

Does anyone happen to know what the plus "+" means on semi-recent Quick hot air station product numbers?
For example, the 957DW+, verses the 957DW.

The "D" designates the digital display/control, and I gather from another thread ("Quick Review: Quick 957 Analog Rework Station") that the "W" means it has a brushless motor instead of brushed.
But the plus vs non-plus is elusive - not even Quick's website has the answer. 

Thanks

[thm_w]

https://www.eevblog.com/forum/reviews/quick-review-quick-957-analog-rework-station/25/

Looks like they've changed the control board inside but from the outside no major differences.

Probably depends on the model #.

[Dave8266]

So I sent an email to Quick USA, and received a reply that the only difference between the plus and non-plus, was that the plus used a different fan motor.
Which (and thanks for your reply by the way), seems to slightly contradict the linked thread that shows other internal changes.