Well I said a long time ago I would in fact touch on space ships for my sci fi even though space travel is actually not often seen in the story (as most people get form point A to point B via portals). I decided to start off with the most tedious but most relevant ones via Grey space ships known obviously as "saucers" at least by non greys. According to Buu their actual name is very long and convoluted and not worthy trying to say using spoken language so they just don't bother correcting it.
Anyway much like there's 4 natural morphs for greys they're... 5 types of ships but one is a fighter type craft that isn't an actual saucer but a different type of ship all together so it doesn't really count! So for info

Survey Vessel- The smallest of all the saucers which is used to, as you imagine, survey planets to gain info about the size and environment of it. They also occasionally collect specimens though that's mostly the job the the Research Vessel. It tends to house anywhere between 3 and 7 worker greys usually though other morphs may be present. This is the type of saucer Buu owns as well as the type that was shot down during the 1947 crash that led to humans become fully aware of aliens within my story. They're without any proper defences but they're very fast to compensate.

Research Vessel- The second smallest saucer which is used primarily to collect specimens and perform experiments often on the native life within those planets. They tend to house anywhere between 10 to 30 worker and nanny morph greys. They have access to to a energy shield as temporary protection from enemies but they're otherwise poorly equip for combat.

Battleship- The second largest saucer designed to help in any conflict. These ships primary function is to stay behind when a Mothership flees from danger to destroy whatever threatened it in the first place. They may sometimes be used to support other species in time of conflict as a secondary function as part of their agreement with the UICA in regards to protecting life in the universe. Smaller models tend to house a few hundred soldier morphs while larger models tend to house a several thousand, each has several Nannies present for medical support and some workers to repair the saucer in emergencies. Battleships tend to move in mix fleets made up of large numbers of these saucers and are consider one of the strongest military forces in the universe. On top of that each houses many fighter crafts which themselves come in different scales; some being rather small and made for a single soldier while others being around the size of a survey Vessel.
*Note: the size comparison used use for the Battleship is the smaller model.

Mothership- The largest saucer by an impressive margin. There exists only 9 of these and each could be compared to the size of a small continent or large country (explaining the lack of size comparison silhouette). Each can house roughly a billion greys of all morphs and contains their queen. This is where basically every grey lives when they aren't doing work that requires travel with the other ships. Its literally a mystery how a species built something this big though it is known it was the ships are over 10 000 years old and are all roughly the same age so they were all built simultaneous over a very long time to say the least. Each ship has its own inner environment and is fully self sustaining. Lacking its own defences it uses battleships to fight its battles and flees using portal technology as otherwise it be far too easy to follow the ship.

And now I move on to something that doesn't involve needing to draw very specific details because stuff like this is pretty draining ;A; So enjoy!