good deal. I'm not sure of the difference either.

I think hay has seeds and straw doesn't

Hay is typically grown as feed for cows/horses/sheep/etc. and is a true grass. Straw, on the other hand, is the leftover of wheat, or oats, after harvest.

Make sure it is straw before using it in the garden. Hay will add weed seeds to the garden, straw usually doesn't. That's a big difference.

If the contents of the bales are soft like dried grass, then it is hay. Straw is yellower, rougher, and has sharper edges.

Coastal hay is much preferred for mulching a garden. It is a lot less likely to contain seeds.
Jerry