I'm deciding to make spaghetti squash today but can't decide what sauce to use: a pasta sauce or spaghetti sauce. I'm sure those are just general terms for many types of sauces, but can anyone give me an idea of the difference between the two? And also, what is marinara sauce?
Marinara sauce is a specific sauce, made with tomatoes, and probably garlic, onions, and herbs.
Spaghetti sauce, in the US, means something tomato-based, possibly with meat. I suppose it's based roughly on marinara or bolognese, depending on what variety you have.
Pasta sauce means absolutely any sauce you can put on pasta. Maybe some people have specific things in mind, certain sauces they use more often, but it's not a specific enough term that you can say "I'm making pasta sauce" and have everyone know even roughly what you mean. In the US, certainly tomato-based ones are extremely common, probably followed by creamy things like alfredo, but there's plenty beyond that.
This is not cut in stone, but I have heard people saying that spaghetti sauce needs to be 'stickier' than just any pasta sauce, because it has to coat the spaghetti enough to get a good balance of pasta and sauce.
You will find additional tricks for that, like not rinsing your spaghetti after cooking, letting it dry completely before adding the sauce, or using some of the cooking liquid in the sauce, so that it has a higher starch content.
That says nothing about the taste of the ingredients, only about the consistency. You can choose your ingredients to make a thicker sauce.
I noticed that letting my onions simmer for a long time, then again letting the sauce simmer for a long time, helps.