There is no EvE Echoes without spaceships, with that being said it is important to understand the different types of spaceships and how they affect your gameplay.
There are different kinds of ships and they all serve different purposes.
Ships in the game are usually categorized by their sizes or functions. You can have ships in the same size category that can have completely different functions.
Example of functions are for example, ships that specializing in hauling. They will have a bigger cargo hold, but have very little space to fit in weapons or other combat modules.
Another one can be a ship which specializing in supporting a Fleet by remotely repairing armor and shield during the battle(similar to healer/medic classes in other mmos).