Imagine coming home from a Halloween party and you see a silhoutte lumbering towards you, moaning something barely intelligable, "Brain, Braaiinn,". You think to yourself, "Oh, someone's been partying so hard the hangover is already hitting him,". as the figure comes closer, a flash of lightning illuminates it.
II. A Necroborg/Zombot/Zombie Robot/Undead Robot/Cyborg Undead/Zombie/Undead Machine is a Machine-Zombie hybrid with mechanical components and properties. Moreover, despite being undead, they have plenty of immunities, and certain weaknesses have faded away. It is also possible that they can transform their limbs into weapons, such as Sub-Machine to Machine Guns, explosive artillery, having a built-in Teleportation/Invisibility/Reanimation device, what have you. While they still have weaknesses that a typical Zombie has, they also have weaknesses that stem from Robots and Cyborgs. A good example of those would be the Husks from the Mass Effect Series.
III. A Zombie Lord is a much more powerful type of Zombie, they are really difficult if not impossible to dispatch, since they have both Immortality, and Supernatural Condition. They are technically living undead compared to regular Zombies. As such, they have authority over Zombies, Skeletons, Ghouls, and especially Zombie Hybrids. A Zombie Lord's birth is quite self-explanatory, but the possibility is that the corpses are controlled by unknown powerful forces, especially giving them astonishing powers and abilities. In IQ standards, their intellect is rather high, with their rational sense, and especially their self-awareness being retained. They still have weaknesses, but they are lowered to lesser degrees, making them resistant to them. They would also may heal themselves via eating flesh (same goes with learning or growth), or just have Enhanced/Supernatural Regeneration. A good example of a Zombie Lord will be Evil Ernie from the Chaos! Comics.