How can you tell whether something is YA or MG?

I have a really hard time with this. Yes, there’s things that make it obvious, but with some books I really can’t tell.
It’s not really that important, but I like to know which category things fall into. I just like to know every little detail about my books,* the characters eye colour, the characters middle name, the author’s name, the genre. And the age category.**

For the most part, I can tell. But once in a while, I come across a book where I have no idea. Is it on the younger side of YA? Or the older side of MG? It annoys me when I can’t tell. I don’t like mysteries. Well, I like reading mysteries, but they get resolved. By the end it’s not a mystery any more. I don’t like mysteries in real life.

Anyways, enough about mysteries. I’m going to talk about some of the books that I just can’t decide. Also I’m hoping maybe by the end I’ll have come to a decision about what age range they fall into. Maybe. Hahaha, I’m very indecisive.

*I’m a bit nosy.

**What’s that called anyways? Age category? Age range? Age thingamabobber? I have no clue.

Circle of Magic

I love these books, but I can’t quite decide where they would fall. They seem a bit young for YA, but they also seem a bit old for MG. So where do they go?

YA-like traits

• They have very complex plots. There’s a lot to them, in a way that isn’t often found in MG.
• The magic is pretty complicated. When I first read the first book, at age ten or eleven, I had no clue what had happened in the climax. There was a lot to it, but all I got was ‘they did something with their magic, and somehow managed not to die’. If that was all I’d understood going in to the later books, I wouldn’t have had any idea what was going on.
• Some of the content seems sort of dark for MG. Plagues (with lots of description). Dead bodies floating in the water after a pirate attack and a shipwreck. Basically, a lot of death.
• I still consider it one of my all time favourite series, even though I’m finding most MG too young to really enjoy it (Totally a YA-like trait I’m sure)

MG-like traits

• Although they act a lot older, the characters are only ten. Which I honestly have a hard time believing. They act older.*
• Although they are dark, and somewhat graphic, they don’t actually seem all that dark.
• They’re on the short side (Too short. I want more *pouts*).

Okay, I still don’t know. That didn’t help apparently.
I think they’re maybe MG, but I’m still not really sure. I’m too indecisive.

*I know, I know, I just said that like three seconds ago.

The Yellow Hoods

This is the series I have on the go right now. I’m pretty sure the first one is MG,* but I’m less sure about the later ones.

YA-like traits

• These are really complicated and confusing. I can barely keep track of all the plot threads.
• A lot of the main characters (the books are told from many, many perspectives) are adults.
• Everyone has very complex motives. That doesn’t sound particularly YAish,** but it makes it feel more mature when you’re reading it.

MG-like traits

• The violence seems ridiculously tame. I don’t really like violence in books ( I don’t dislike it either, it’s just there. I don’t care one way or the other.), but seriously, the villain attacked you with… Air guns? That shot air at you? Wut?
• When you are reading about the younger characters, the books seem very young.

Looking at this, I feel like they’re probably YA, but they don’t really feel like YA. I don’t know. I give up.

 *Although I read it a year ago, so I don’t remember it very well.

**Totally a word.

What about when the first book in a series is younger than the rest of the series?

This is something I find when a series spans over a long period of time (6+ years), the first book often feels like MG, but the rest of the series is obviously YA.
But I don’t want to split up the series. Even though I don’t shelve my books by age or anything. I just don’t want them split up in my brain… It’s a bit silly, really.

For instance, one of my favourite series, Song of the Lioness , follows the main character as she becomes a knight. The first book takes place from the time she’s ten, until she’s thirteen or fourteen. So it’s younger, on it’s own, I would say it’s probably MG. The later books, however, are written for an older audience, they follow her from fourteen, into her early twenties. All of them are definitely YA.

So where does the first book go? Is it MG, or is it YA? I say YA, but I can’t really tell.

Have you read any of these? What age thingy do you think they fall under? What is the proper name for age thingies anyways? Are you incredibly indecisive like me?