Rules vary depending on the level of knowledge the students have and the person holding the competition. The main consistent rule across all variations is that the egg cannot smash on impact. Some level of cracking may be allowed, though there is usually some consequence such as points being docked. The rules may also choose to focus more on protecting the egg from a drop from a high height or judging by aim in the case of launching an egg.
Materials in egg drops vary. In some cases, the main rule to follow regarding materials is size. The apparatus used to launch or catch or protect the egg cannot exceed a certain size, and as such neither can the materials. In college competitions there may be no rules on what materials can be used whereas in lower grades the students may be forbidden to use certain materials or restricted to a set list of materials.
A "naked" egg launch is an egg launch in which instead of being protected during the drop, the egg must be dropped into some sort of apparatus that protects it from the fall. Again, the main restriction here is that the apparatus cannot be bigger than a given size, as this competition tends to focus on aim. The height in this competition is also usually lower than a normal egg launch to account for the change in difficulty of aiming as opposed to dropping an entire apparatus.
There are different ways to score an egg-launch project. Some schools or institutions will use a very detailed scoring method to account for cracks versus breaks, or small deductions for the apparatus breaking or parts of the apparatus coming off during launch. Some schools will required detailed reports on the methods used to invent and create the apparatus. If a target is used, different parts of the target may warrant different point scores when hit.