How to tell if the walls are Ash or Birch?

I saw on some other thread someone talking about Oak being similar grain to Ash. Do I read this correctly to look for 1/8" sheets for curved surfaces and 1/4 sheets for interior walls? Or is the preferred 1/8" all walls interior?

Some people including myself ended up replacing with birch and sanding down the old ash and amber shellacking it all to match. There is still a difference in the grain but the uniform amber shellac helps it blend together.

Alternatively, you could just emphasize the difference in the woods by using another shade of finish on purpose. We had a gorgeous mid-century home that did just that using a combination of cedar and black walnut. It was stunning. And though unconventional, this could be, too. We could NEVER come close to matching the grain in our Compact’s paneling. When we replaced it, we found panels that have a distinct heart shape to the grain. Rather than tear all of it out, we would probably go for a contrast.

If you can save some of the original, don’t just think outside the box, throw the box out. If anyone asks about it, just say, “It’s a feature.”