I don’t know how I missed this before, but the name Imperial and Empire seems to be used interchangeably. The race is named Empire, but all of the ships are labeled Imperial.
Well, the words are related to one another. Something “imperial” is, by definition, related to an empire.
The temptation to rub this in is almost overwhelming 
Easy mistake if you’ve never come across the terms used in context before. Easiest analogy you might know; the Stormtroopers in Star Wars, who belong to the Empire, are referred to as Imperial Stormtroopers.
Thanks, that does explain it. I didn’t realize the words were directly related like that.