Ciao Marco, I think they are the same word. Congratulations on Vincenzo Nibali winning le Tour de France today. Our concept is to build a skyscraper using a 3d printer. The conception of using a 3d printer, to build the skyscraper, failed miserably.

No, they aren't synonyms. Conception means the beginning of something : either when a baby is conceived inside its mother, or when people first begin to develop an invention, a product or a project. A concept is an idea or a theory. Is this not the same difference as in Italian? Between 'concezione' and 'concetto'?

Let's have an example: The Immaculate Conception of Christ the King is not merely a nice concept but is in fact a central belief of the Catholic Church. Now, how do you say that in Italian?