What is the difference between istila and tafkheem and istifal and tarkheeq

Question
What is the difference between istila and tafkheem and istifal and tarkheeq.
Answer
The characteristic of * is an inherent characteristic of seven letters.  This characteristic is defined as:
Directing pressure of the letter to the roof of the mouth due to an elevation of the deepest part of the tongue when pronouncing an * letter.
All the letters in the group of * have tafkheem.  These letters are the those which form the words:
is the opposite characteristic and it is defined as: The absence of pressuring the letter to the roof of the mouth due to the lack of raising the deepest part of the tongue when pronouncing a letter of .   The remaining letters which are not in the group have .
All of letters of the group have tafkheem but not all of the letters of have the fixed state of tarqeeq.  Most of the letters of tarqeeq but some such as the راء ، ألف ، واللام  sometimes have tafkheem and sometimes have tarqeeq. 
So tafkheem and tarqeeq are not intrinsic characteristics, but * and are intrinsic. 
See also:
http://www.abouttajweed.com/tajweed-rules/53-tafkheem-and-tarqeeq/57-tafkheem-and-tarqeeq-part-1