Grateful, or thankful? What's the difference?

So, I'm thinking of things I'm thankful for, this being Thanksgiving and all, and as I'm toting up all that's terrific in my life, I start wondering: am I thankful, or am I grateful? 


For example, am I thankful for the luxurious new Italian wool throw that my cugini sent, or am I grateful that they left so I can have my room back? Furthermore, did Mom feel embarrassed that I had chewed holes through the old throw?

I will elucidate. The definitions, then:
1. grateful: feeling or showing an appreciation of kindness. So I would be grateful for a new wool throw to wrap 'round my tired self. How terribly kind of them to think of me.
2. thankful: pleased and relieved (no kidding!) Obviously, I'm thankful that I have my room back.
And Mom will be embarrassed once my dear cugini see just how grateful, and thankful, I am. Cozy, too.

Happy Thanksgiving!