What is the proper word/term/expression to describe a dish that appears to be something different
I believe the most common term, especially for foods that just visually look like another food, is Trompe-l'œil.  While the Wikipedia article linked focuses on other forms of art, the word is still applied to foods.

If you google "Trompe l'œil food", you will find many examples of the term in use.

Note that Google seems smart enough to handle either "œ" or "oe".