Hay is alfalfa or grass that's been harvested. Cows eat it.
Straw is wheat stalks. People use it for bedding - meaning they put it down so cattle can lay down on it and be more comfortable. It also kind of soaks up the manure. It's consistently changed and added to in the pens.
It's easy to understand why people confuse them. They look similar, since they're both stringy and usually in bales. Hay is green and straw is yellow, but unless you're comparing them, you wouldn't really think about the differences.
Children's books often get it wrong, because 'hay' makes for a much better rhyming word. But we have a book that talks about the cow lying down in the 'soft, sweet hay, in the cozy barn, at the end of the day.' I have to substitute 'straw' when I read it, even though it doesn't flow nearly as well. Why? Because hay is much too valuable to have cattle sleeping on it! It'd be like me going to sleep in my bed made of caviar. You know, if I liked caviar.
Farm news - just awaiting calves, building a barn, and waiting for the next cutting of alfalfa. Translation - everyone is busy all the time.