I basically just answered an almost similar question for someone that had a broken outdoor sensor array.
https://www.wxforum.net/index.php?topic=36601.0Basically the only difference is the outdoor sensor array is different. The WS-1550-IP uses the Osprey sensor array also called the WS-2902-ARRAY. The WS-1401-IP uses the WS-1002-ARRAY sensor instead.
Both the WS-1401-IP and the WS-1550-IP use the ObserverIP device as the console to receive the data from the sensors and connect to the Internet. It is the exact same ObserverIP running the same firmware. Which allows someone to change the outdoor sensor array from the older model to the newer model.
The WS-1002-ARRAY is the older model ... used in the WS-1401-IP, WS-1002, WS-1201(-IP) and many other discontinued models.
The WS-2902-ARRAY (Osprey) is the newer model ...used in the WS-2000, WS-2902A, WS-1550-IP, WS-1900.
See this post to for more info:
https://www.wxforum.net/index.php?topic=36296.msg372434#msg372434Therefore I recommend the WS-1550-IP without reservations absolutely. No reason at all to get the WS-1401-IP.