What is the difference between marinara and spaghetti sauce? The title pretty much says it: What is the difference between marinara and spaghetti sauce?

I Googled and got a bunch of hits but none of the answers left me feeling like I actually understand the difference. If anything, I'm more confused now than when I started. The one thing that a few of the answers I found had in common was the idea that marinara sauce is simpler, with fewer ingredients than other tomato-based sauces. Still, the idea does not present the full picture. I guess another way to approach this question would be to ask: What would one add to "marinara" sauce to make it "spaghetti" sauce?

Thx
Marinara is a style / kind of a sauce that originated in Napoli usually made with tomatoes, garlic, herbs, and onions. A spaghetti sauce only says where to sauce is used (obviously on spaghetti) but doesn't say anything about what the sauce is exactly like. 

There are many dishes which are basically spaghetti + sauce:


Spaghetti alla marinara – which literally translates to "spaghetti mariner's style"
Spaghetti aglio e olio – "spaghetti with garlic and oil", originated in Napoli
Spaghetti alla puttanesca – "spaghetti whore-style"
Spaghetti alla Carbonara – "spaghetti coal worker's style"


and, uhmmm...


Spaghetti with meatballs – an Italian-American invention