Here are some more detailed differences between spacecraft made by Emerald:
In case you don’t already know, there are tier goals where you have to reach a certain career score. Flying missions will increase said score, and once you’ve earned enough, you will advance a tier and be rewarded keys. You can check your tier progress in detail on the left side of your Profile screen.
I’ll skip explaining what benefits do higher tiers give, as others have already explained it.
Not at all, not even in Space Race, despite what others are saying. In that mission, time matters over score, so your rank will be higher the faster you complete it.
If I recall correctly, in the first versions of the game, the type of exhaust you have actually depended on the thruster you have equipped on your flagship, but the exhausts later got separated into spacecraft customization.
Either use the Accumulator, or equip Coolant Canisters. A lot of them.
It has to be intentional. I don’t think it represents anything, though.
That’s why there’s a fan-made guide out there, go check it out!
Damage Amplifiers.
What Bonnie said.
I hope these answers satisfy your questions and concerns!