What makes the difference in engines?

I'd like to know how companies (ford, Chevy, dodge. Ect) change the engine to make them better besides how many cylinders they have. How do they make different sounds, more or less power? Sense they all have the perfect air to fuel ratio from the factory that would make a difference right?

Actually, the fuel air ratio can be slightly changed to improve power, thermal or consumption efficiency.
on top of this, things like how restrictive the intake and exhaust are (including the valves), how the fuel is mixed in (a jet, fine mist, or other methods) or even the shape of the cylinder head (Dodge's Hemi refers to the hemispherical cylinder head they use) all change the characteristics of the engine.

engine sounds are usually characteristics of the cylinder count and arrangement, engine size, and exhaust shape.
the overlap (or lack of it) of combustion cycles dictated by the cylinder count and arrangement will change the way an engine sounds because of the pattern of puffs of air going through the exhaust and frequency explosions inside the engine.
the engines' size will also increase the volume and sound of the engine. More air being pushed out means more volume.
lastly, the exhaust itself which acts like a musical instrument will also change the volume and tone of the sound. By changing the size and length of the pipes and how restrictive the muffler is, car companies can change how the engine sounds. Supercar companies like Lamborghini, Ferrari, or Mclaren have engineers whose sole jobs are to perfectly tune the exhaust sound coming from the engine. (a large part of the supercar ownership experience comes from the sound and if a car sounds bad, the owner might not be too happy)

beyond this, there are many different aspects of engine performance that can be really interesting to learn.
if you want an easy to understand explanation, of a lot of this stuff, check out this YouTube link.

https://www.youtube.com/...gExplained

This user has a lot of videos explaining in simple terms how cars work and what affects performance and how. He has playlists ordered in a good way so that you can easily build up your knowledge of cars. He's also very good at answering questions that you may leave in the comments section. I learnt a lot from him.

Every engine is different. Not just from different manufacturers. Take Chevy for an example. The Chevy small block is the block for all their v8s the block is the same size for all of them. But they can range from a 4.3 v8 all the way up to the 400 sbc. The difference is things like bore, stroke, piston size, compression. What they're made of. The sound mostly comes from the exhaust. If you cut the exhaust off they would all just sound pretty close