Is there any difference between getting dissolved and getting dissociated?
This is a simple logical and semantic problem, which is not a problem at all. Your professor is right and wrong- both at the same time. He is creating a classification which does not exist and which is meaningless.

Look at the word origin of electrolyte:


  Etymology from OED: &lt; electro- comb. form + ancient Greek λυτός that may be
  dissolved, soluble (see -lyte comb. form). Compare electrolysis n.,
  electrolyse v.
  
  and the portion -lyte "&lt; ancient Greek -λυτος, combining form (in e.g.
  εὐδιάλυτος : see eudialyte n.) of λυτός that may be dissolved, soluble
  &lt; λύειν to loose (see lysis n.) + -τός, suffix forming verbal
  adjectives. Compare French -lyte, German -lyt.
  
  A substance which gives rise to ions when dissolved (typically in
  water) or fused; a liquid or gel which contains ions and can be
  decomposed by electrolysis; spec. the conducting fluid used in a
  battery.


Does this solve the semantics problem?

By definition, an electrolyte is soluble in a given solvent. It is also understood among electrochemists that an electrolyte is added to a solvent to impart conductivity to that solvent. I will never call sugar an electrolyte because nobody would use sugar to increase conductivity of water. You should ask: Does a given substance produce ions in a solution? If yes, it can be called as an electrolyte. 

Look at this logic: grapes is a fruit but not all fruits are grapes.

Electrolytes are soluble in the solvent, but not all soluble substances in that solvent behave as electrolytes. Anything which produces ions in that solvent, can be labelled as an electrolyte.

Q-1 If solubility and dissociation are different then what would be the criteria for getting dissolved and what will be criteria for getting dissociated (for me the criteria for getting dissolved is dissociation).

The measure of dissociation is conductivity. How much electrical resistance is offered by that dissolved (and dissociated) substance in that solvent

Q-2 how would you arrange the following in increasing order of 1.solubility 2.dissociation

NaCl, MgCl2, FeCl2, ZnCl2

There is no correlation between solubility and dissociation.  If I want to study their dissociation I will measure the conductivity of their solutions systematically.