Which interstellar empire would win in a fight?

I see a lot of parallels between the Combine Empire and the Gem Empire from Steven Universe, so I have to ask, which empire would win and what would happen to the loser's empire?

I think the Combine would beat the Gems, because the Combine have more interdimensional forces to call upon, they have the capability to destroy Earth in 7 minutes, and they can mass produce forces and incorporate Gem forces into their own ranks.

they have the capability to destroy Earth in 7 minutes

hours*

they have the capability to destroy Earth in 7 minutes

hours*

"It'll be the 7 hour war all over again... except this time we won't last 7 minutes!" - Eli Vance

"It'll be the 7 hour war all over again... except this time we won't last 7 minutes!" - Eli Vance

Earth prior to the Combine invasion is definitely far stronger than Earth *two whole decades* after the invasion.