Pretty much, one server has its own save-data stored in it and the other has its own. Making a bridge between both is indeed possible, yet not for us, not now atleast. Main reason behind this is the lack of resources we have to present such a feature, other being the amount of data traffic there will be between both servers on a coding and hardware capability level. Imagine if you will; You have picked up a 80 berries from all the crop pots across kanto in blue server, and you decided to switch servers, the last save data of your account in red server will overlap with the one in blue server and it will have to be edited out with the current one, while there is already 1900 data traffic going on continuesly.
On topic : The reason why save datas are seperated is, considering already existing playerbase we had on the server and the ongoing dissatisfaction complaints we got from the new players that they were unable to play, including the increased queue rate on one server. Adding another server that has no save data stored for anyone, will ultimately sway already worked around players that have over 100-200+ hours and give new players more space to play on. Which worked pretty well so far.