These five-foot tall, chrome robots are shaped like Lexington (and sound like him too), and by 2198, have become extremely popular with the people of Earth. Each LXM is linked up by satellite with the Master Matrix in Antarctica, allowing it to draw upon its information files when needed, making them very useful. 
After the Space-Spawn stole the Master Matrix in 2198, however, the LXM robots were left on their own. Each one still possessed a powerful computerized brain with crude artificial intelligence and long-term adaptive programming; however, they could now only call upon the knowledge that they had at hand and must learn through experience.
Two particular LXM robots, LXM-994 and LXM-1057, are to play key roles in Samson's resistance against the Space-Spawn, and while at first they will be indistinguishable, over time they will develop unique personalities. 
Behind the Scenes
The two main LXM robots are both named for important years in Gargoyles Universe history: 994 was the year of the Wyvern Massacre in which most of the original Wyvern Clan were killed, and 1057 was the year that Demona's Clan was destroyed by Canmore after Demona betrayed Macbeth.
Within the show they are, in fact, the number designations were issued as a factory standard, so its unlikely that the robots are aware of their designations' "resonance".