I looked it up, but I don't know if this is like "Pajilla" and "popote" where 2 countries have different words for the same thing...

Cobija or frazada are meant to keep you warm. In Chile we only use frazada.

Colcha either is for decoration or both for decoration and keeping you warm.

They can intersect, as both can be a bedspread or blanket, but where they differ is that if you want to specify that it’s a bedspread or blanket that is quilted, it’s a colcha.

Cobija is related to the verb cobijar, which also can be used in contexts wider than blankets; that is, contexts relating to shelter or to cover in general.

At least that’s the usage I know from Mexico; I don’t know if it could be different in other places or countries.

For what it's worth, in my neck of the woods (Northern Mexican/Southwestern U.S. Spanish) we mostly use "cobija" to refer to blankets, while I've only heard "colcha" used to refer to a tapestry on a wall.

Colcha is bedspread, so a specific type of blanket. Cobija is a blanket in general but not just a blanket it can be a shall or begging in general. I really like SpanishDict for this kind of thing. It gives you a lot of the definitions and often indicates which regions or countries the word is used.

I think colcha is a "quilt" and cobija (same as manta) is a "blanket"

Yes and no

You’re asking the wrong question or looking at it the wrong way

If you want to learn to speak Spanish in any practical sense, you need to realize that words like these change from country to country and even from regions within a country

You have to learn to emulate the usage from the people you happen to be talking to: Peru, Mexico, Argentina, etc.

Another tip: there are more generic terms that almost everybody recognizes, such as “sábanas” and learn to use them like “cómo sábanas, pero más gruesas”. Anybody can understand that

In Colombia, a "colcha" is the fabric used to cover the bed (also "cubrelecho" or "sábana" are used)

"Cobija" is the blanket you use to cover yourself with when sleeping, most of the times it's intended to keep the heat during the night.

Yes, at least in Mexico. You can get technical about it, but in a real context you can use either.

As already mentioned, colcha is the comforter/bedspread. On the same topic, cojín is the decorative pillow vs. almohada which is the pillow for your head.

My parents are from Chihuahua. Colcha is a quilt, thicker with padding and double sided. Cobija is blanket. I’m Mexican American from southern New Mexico.

What you describe as a colcha is what I would call edredón

I do suppose "quilt" could be an accurate translation seeing as it was pretty thick. My family's mostly from Sinaloa and Sonora, so maybe that could also explain the difference.