What is the difference between AOS vs NVC filing for EB-5?

It is best to all file at the same location if possible. Otherwise Principal would need to get green card, file the I-824 with the I-485 to have consulate notified of approval and then dependents abroad would start their process - more than doubles the processing times. Once the I-485 is filed and you have a case number, you can check USCIS Case Processing based on the Service Center case number or Field Office closest to your residence if there will be an interview by selecting I-485 and then appropriate location.

If someone enters on a B-visa with an intention to file an adjustment, that can result in visa fraud. If someone enters on a B-visa for a legitimate B-visa intention and circumstances change, then after 90 days they may be eligible to adjust. In a case such as yours, it makes sense to finish the case off in Guangzhou. We got so many appointments for Guangzhou so its looks like finally the cases are being scheduled. My guesstimate for a newly filed adjustment is at least 1-2 years and work and travel permits are taking at least one year to process - but accurate times are hard to provide since they change constantly.

That sounds like a Follow to Join process if the spouse continues at the consulate after the primary adjusts in the U.S. USCIS posts processing times on their website, split by form type and filing location.