Picture Book question

I am not an expert by any means and I am based in the Uk so my take might be difference but 'picture books' are usually 32 pages long, 12-14 double page spreads and is usually under 1000 words long. the pictures tell their own story. Unless you are a profesional illustrator you should not attempt to illustrate them yourself nor attempt to find your own illustrator.
In a picture book there should be interplay between text and picture and you do not include anything in the text that can be shown in the picture.

Illustrated children's books are quite different. Many non fiction books are illustrated, but again you should keep the word count down and make sure that the text complements rather than replaces the need for illustrations.
It sounds like you have a non fiction piece as fiction kind of requires a story. If there is no story it is probably best to market it as non fiction. IMHO

Also take a trip to the bookstore to look at both picture books and non-fiction for young kids to get an idea if your book fits both.

Story is important. Make sure you have one if you are going after fiction publishers.

I don't know what your question means. There are illustrated texts for older children but the term 'picture book' tends to refer to those books designed for pre schoolers .If you mean illustrated texts I think the issue of story still obtains.

Well, I'm a Brit so everything is different over here...

Here's my understanding, for what it's worth, I'm not 100% certain:

Early picture books are for preschool-age kids. They tend towards concept books, with very simple language and a minimal story. Something like Brown Bear, Brown Bear, that a young child can memorize easily and chant along with, books that stand up to many, many re-readings.

Picture books are for slightly older kids, kids who have enough attention span to follow a complete short story. These may have a twist ending, richer vocabulary, and not be as easily memorized. An example might be Dogzilla by Dav Pilkey.

The current market is very, very limited for longer picture books that are aimed for kids above the age of 7--unless the book is non-fiction.

What you have sounds like a non-fiction book. You don't have a plot, from what you've described, so it's more of a concept book. So the next question would be, what is the reading level? And how closely does the reading level match the interest level? In other words, would it be something a 7-year-old could and would want to read to herself, or is it meant to be read aloud to a younger child?

My expertise here is from a teacher's perspective, not a PB writer's perspective. If you are not already a member of SCBWI, I would highly recommend it. They have so much information to offer on picture books, you'd be sure to get the answers you need.

Just one more thing. Jud is probably right about the picture-book/early picture-book thing, but my initial thought was that a picture book was one that was meant to be read to a child, while an early picture-book might be one meant for early readers to read themselves, limiting the vocabulary. I don't have any information to support this, but since none of us seems certain, I wanted to post anyway--just in case.

And I think there is a decent market for your type of picture book. Anne Rockwell has written several in similar style (Fire Engines, Cars, etc.) which I believe are marketed as non-fiction.

Hope this helps . . . but I'm not making any promises.