China is a special case with Azure CDN Products, as there cannot be POP locations inside China. You can get Azure CDN Offerings from Azure China which do have locations inside China.
For the differences in delays, each CDN offering has different POPs near China, and will be served from the closest location. PoP locations from Azure CDN by Akami are not disclosed, so it will be difficult to get an exact answer on the routing.
For the first comparison, the Akamai image is almost definitely being served inside China, which is not possible with the Azure offering (As described in the first link), but would likely be more comparable (if not identical) if the Azure China offering were used.
For the 2nd comparison, they are two different offerings and will have different PoPs and latencies, so this is expected. Please let me know if I can provide any more information.