I'll try ...
Quick service Dining plan = per person per night stayed
2 Quick Service meals
1 Snack
1 resort refillable mug
So this would get you 2 meals at any counter service establishment i.e. Cosmic Rays or Pinnochio's Village Haus (or a hotel QS outlet ie All stars food court)
That meal is an entree plus soft drink plus dessert
The snack is an item such as an ice cream, coffee, cupcake etc.
Regular Dining Plan - per person per night stayed
1 Quick Service meal
1 Table Service Meal
1 Snack
1 resort refillable mug
This gets you the 1 QS meal and snack and mug as above but replaces the second QS with a Table Service meal
The Table service meal entitles you to an entree and dessert and soft drink from any table service restaurant i.e. T.Rex or Mama Melrose etc.
But beware the TS meal does not cover your tips ( approx 20% is usual) and any alcoholic beverages.
Deluxe Dining Plan - per person per night stayed
3 meals (any combination of Table service or Quick service)
2 snacks
1 refillable mug
Really for serious foodies ! Or very very hungry people
Real foodies use this sometimes as the posher end of the restaurant scale, ie Victoria and Alberts, Narcossee's and other Disney Signature restaurants charge 2 credits for one meal.
We used the Regular plan last year and found it was plenty of food - we had unused QS credits at the end of 14 days.
Hope this helps a little. My trip report 'seven years is too long' has details of the restaurants and credits we used.
Tony