Is there a difference between thankfulness and gratitude??

As you may have gathered by "It's the Little Things" being thankful and showing thanks is very important to me.  My Grand mother always emphasized the power of saying thank you.  If she gave me a mere small piece of candy and I did not acknowledge her giving with a thank you she would mock my childlike voice and say "Thank you grand mom".  If one of her seasoned friends would give me a gift she would remind me to write them a thank you card telling them how grateful I was for their thoughtfulness.  She also taught me to take care of the gift.  No gift ever went without showing appreciation.  I can even recall watching grand mom sitting at the kitchen table writing letters to store owners, leaders of her church, and politicians thanking them for any act of kindness.  Grand mom was big on that.  At the time I did not know the magnitude but today I am thankful for this lesson on gratitude.  Every gift warrants a thank you!     
Merriam Webster defines gratitude as the quality of being thankful.  I am intrigued by this word “quality” in the definition. Quality is a measure of excellence, a richness, it implies the best, it is free from defect.  Gratitude is giving your best form of thanks.
There is an intelligible feature that makes a thank you more than a mere thank you and turns it into gratitude: the heart.  Gratitude is high quality appreciation that involves feeling. 
To be thankful is to be mindful and take notice of “the little things”.  Thankfulness always has a giver and a receiver.  Someone or something caused the appreciation exchange.  Gratitude, on the other hand, is the feeling or the sense of being.  With gratitude you are always in that state of appreciation.  It is about more than the gift…it’s about the thought behind the gift.
I can sum it up to say that gratitude is this feeling that I feel in my heart.  When someone gives me a gift or does something for me  I immediately go into a gracious space.  I think about the thought behind the gift.  I think about the time behind the gift.  I think about the sacrifice that may have occurred in order to give the gift.  I am reminded of my love language and my tank is filled.  I feel it in my heart, I value the gift and honor the person for their kindness and thoughtfulness.  
I don't know about you but I can't count how many times I say thank you to my Heavenly Father in a day.  I am thankful for waking up, I am thankful for family, I am thankful for a vehicle and a home.  I am thankful for a job that pays the bills.  But as I learn more about gratitude and thankfulness how can I possibly use the same thank you that I say to the gentleman that held the door for me the same way I said it to my Heavenly Father when He blessed me with life.  To me they are different forms of thank you...they have a different quality.  They come from a different place. Yes we are thankful for the gentlemen that held the door but I am gracious for the Father that opens all doors.  We have gratitude for His grace and His mercy.  Grace, Mercy, Blessings, Honor (I could go on and on) activate gratitude from the heart.  
What are you grateful for?