Respuesta :
					                   in my opinion....the heaviest is the superlative degree to describe something....and to make it more emphatic ...most is added ! 
but actually only heaviest is the correct form of adjective!
					                
					             but actually only heaviest is the correct form of adjective!
					                   You asked:
_____________________________
1) What's the difference between these two expressions ("most heavy"; vs. "heaviest"?
___________________________________________________________
Answer: "most heavy" is grammatically incorrect; whereas "heaviest" is the grammatically correct superlative form of "heavy". The grammatically correct comparative form of "heavy" is "heavier".
___________________________________________________
2) Which one is grammatically correct?
____________________________________
"Heaviest" is the grammatically correct version, in the superlative form; and "heavier is the grammatically correct version, in the comparative form.
"Most heavy"—or "more heavy—do not exist! (and are grammatically incorrect!).
					                
					             _____________________________
1) What's the difference between these two expressions ("most heavy"; vs. "heaviest"?
___________________________________________________________
Answer: "most heavy" is grammatically incorrect; whereas "heaviest" is the grammatically correct superlative form of "heavy". The grammatically correct comparative form of "heavy" is "heavier".
___________________________________________________
2) Which one is grammatically correct?
____________________________________
"Heaviest" is the grammatically correct version, in the superlative form; and "heavier is the grammatically correct version, in the comparative form.
"Most heavy"—or "more heavy—do not exist! (and are grammatically incorrect!).
 
					                  