Where is a conjunction and it is used to indicate a contrast between two facts or ideas.
- Whereas + clause
- There must be two clauses with whereas
- Whereas + phrase: incorrect Phrase (a group of words with sense but without subject and verb)
Few students scored very high whereas few less: incorrect
He is here, whereas I was looking for him there: correct
Unlike is a preposition and it is used with a noun to show dissimilarity.
- Unlike + noun
- Unlike + clause: incorrect
Unlike the teacher behaved, the students showed decency: incorrect
Unlike the teacher, the students showed decency. Correct