Do the Shipyards have a type or model number associated from canon? 1, 2, 3 & 4 aren't really model names and supposedly in he future R&D of alternate shipyards would be cool even if the provide a similar purpose.
Makes it very hard to suggest descriptions is all..
Most of our shipyard images, from what I can tell, were stolen from other games. Most of the stations were in general, and they have no names. If you are looking for our stations on the wiki, you are no going to find a lot of them. My suggestion would be to just make up four descriptions, saying they were developed for bigger ships as the need arose.