All the responses so far have been fine. Let me add just a few more things.
As one poster said, some hybrids are closer to road bikes than others. If you wanted to convert a hybrid to a road bike, perhaps the biggest issue would be brakes. The hybrid wheel has a wider rim and uses linear pull brakes while road bikes use side pull brakes. Wider rims require linear pull brakes. The wheels on a hybrid are heavier than road bike wheels and you won't be able to put road bike wheels on a hybrid even though they are both 700c wheels because the rim width would be too narrow. Then when you put on the drop bar brake levers, you would find that they wouldn't have enough pull to effectively close the brakes. (BTW, replacing a drop bar with a flat bar and hybrid brake levers work fine with side pull brakes - in fact, think the hybrid brake levers improve the road bike brakes.
I know I will get yelled and hissed at for saying this, but there is little advantage in drop bars. People will talk about less wind resistance, but that is only true if you ride in the drops and most people rarely ride down there. Others will say that drops provide greater hand comfort because they offer multiple hand positions. However, a good set of ergon grips with short bar ends will give you greater comfort on long rides. Also, a flat bar will accommodate a mirror much better than a drop bar, and having a good mirror really, really helps.
My comments are based on my personal experience. I have a hybrid, I have road bike with a flat bar conversion, and I have a drop bar bike as well. Each bike has its strengths, but if I had to pick just one bike, it would be the flat bar road bike (Specialized Sequoia Elite).