@Wiw Sprite wise, not much. Guessing about 85%-90% the same. Different loading and title screens. I did think about combining both games together but various sources on the internet class them as different games... Talked about it a bit here.

Game wise a fair bit. Both have different music (F-16 recycles the music from Motorcross Simulator), both have different HUDs, both have different levels (F-16 starts in the desert, MiG starts at the Woodland), MiG has a scaling effect when your plane explodes and is harder. F-16 supports the Magnum Light Phaser so you could shoot at the enemies like a light gun shooter that wasn't in MiG. AFAIK F-16 was released earlier while MiG was later (later got a NES port that's also here). The games have a messy timeline (Codemasters released F-16 on the Spectrum apparently as a compilation only game, then Mastertronic re-released it on the Spectrum with Magnum support and got an Amstrad version, Codemasters released MiG themselves on both with the claim "NEW RELEASE") and there was another Amstrad game that had a similar fate... Bumpy by Loriciel but it was brought back to the CPC as Pop-Up by Infogrames as they also handled the Amiga/Atari ST/Game Boy versions.

I'm actually surprised no one called out Supersonic Software for this back in the day for releasing two very similar games.

So wait, what's the difference between this and the F-16?