What are the differences between a schmitt trigger and multivibrator?

comparator will change its state when the voltage exceeds a threshold it will return to the intial state when the voltage drops below this threshold.

schmmit trigger will change its state when the voltage exceed a threshold and willl not return to the intial state until the voltage drops at a certain value below the initial threshold. The s the reluctance of the schmmit trigger. Something like inertia in mechanics. That's why Schmit trigger can oscillates. Something somehow similar to the negative resistance in diodes which make them oscillates.