After tons of page read I was not able yet, to find the difference between these 2 RE:
Rather to have a psecific answer here, I would like to have some link to some official documentation where is clealry explaind the meaing of UB or S or B, as per naming above.
Also a general research on https://www.juniper.net/search/secure/ did not provide any info.
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.
However, the product description is same for all the below REs:RE-S-1800X4-32G-BBRE-S-1800X4-32G-RRE-S-1800X4-32G-SIf 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,RahulPlease mark my solution as accepted if it helped.