Hi,
Yes, there isn't any specific document that describes the difference.
Actually, the extensions like S, UB, BB, R, WW does not impact the functionality of the routing engine RE-S-1800X4-32G.
They have some meaning but that is useful for Juniper logistics team while dealing with your RMA.
If you have a look at the below TSB16815, you will find that R refers to redundand, S refers to Spare, UB is Upgrade and so on.
https://kb.juniper.net/resources/sites/CUSTOMERSERVICE/content/live/TECHNICAL_BULLETINS/16000/TSB16815/en_US/TSB16815.pdf
However, the product description is same for all the below REs:
RE-S-1800X4-32G-BB
RE-S-1800X4-32G-R
RE-S-1800X4-32G-S
If you received an RMA from Juniper with a diferent model, you can always contact JTAC and logistics team to get a clear explanation.
If still you need more details, I would suggest to contact JTAC.
Regards,
Rahul
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