Everything is clear now about AMD Renoir APU family. There are three type of APUs under Renoir branding and they have their own codenames. Thanks to Tum_Apisak twitter user for big clarification. All three belong to 7nm process technology based Zen 2 architecture design and desktop APU is fully compatible with existing A320, B350, X470, B450, X570 and upcoming B550 chipset mainboards.
First of all, AMD Celadon is obviously low powered 10-25W TDP mobile Ryzen 5 4500U APU with 6 Core 6 Thread configuration according to footnotes AMD provided in their Pro vs Consumer APU comparison table.
Secondly, AMD Artic APU codename refers to upcoming Renoir 7nm based 8 Core 16 Thread Desktop APU with only 35W TDP and it was leaked months ago by _rogame and komachi_ensaka. Specs and performance wise, desktop 7nm Artic APU is expected to beat GTX 960M and MX150 laptop discrete GPUs in graphics and demolishes 8 Core i7-9700K CPU in powerhouse. It was allegedly found in ASRock X300M-STX barebone SFF PC with only 3.5GHz base clock speed.
Lastly, upcoming and fastest low powered Ryzen 9 4900U with 8 Core 16 Thread monster configuration is confirmed to be AMD-Majolica RN, that means it’s a top of the line ultra low powered APU running at 1.8GHz base and 4.3GHz boost frequencies. By far, Ryzen 9 4900U is expected to destroy any upcoming Intel Tiger Lake CPUs for laptops. Graphics performance will be packed with 8 Compute Units (CUs) to dominate Intel Iris Plus and DG1 integrated graphics.
Source: Tum_Apisak via Twitter