The top one is 20mm Oerlikon most likely U.S., primarily for antiaircraft use. The red projectile would be High Explosive/Incendiary. The bottom one is most likely German also primarily Antiaircraft, and it's projectile is also High Explosive. Of course it is better to have experts handle them, but you might just gently see if the aluminum nose piece unscrews. They are both right-hand thread. Most shells mounted on boards have had the explosive contents removed. If they won't unscrew with your fingers, assume they are still filled with explosive. If they do unscrew easily, look inside to see if they are empty. If you don't feel comfortable doing that, turn them over to the military or police. If the nose piece (fuze) does unscrew, but the interiors are filled clear up to the fuze, it is most likely explosive and you need to get them to the police or military.
You didn't mention if the primers on the cartridge cases were still live. Also if you shake the rounds, and hear powder shaking around inside, that is a clue that they might still be loaded and live.
