What is the difference between Lima Beans and Butter Beans?

I have a recipe that calls for both. I know lima beans but I've never heard of butter beans. I'm in Canada.

I am moving this to AnswerPool's kitchen, in the Cooking forum.

From AnswerPool's wonderful (and someday-to-be-completed) Kitchen Glossary -

Butterbean - (aka Haba bean, calico bean, Pallar bean, Burma bean, Guffin bean, Fordhook bean, Hibbert bean, Java bean, Sieva bean, Rangood bean, Madagascar bean, Paiga, Paigya, prolific bean, civet bean and sugar bean) - basically, a type of lima bean; beige in color, creamy, and somewhat, well, buttery in taste; larger than green limas

Thank you for the explanation (and for moving my question to the right place ... I got lost here in this forum).

So they're the same type of bean only the butter beans are larger. Thank you for your help, much appreciated.