Only the significant sensory inputs enter the Short-Term Memory (STM) through maintenance rehearsal. On the other hand, some items in STM enter the Long-Term Memory (LTM) after elaborative rehearsal which makes information meaningful and connects the same with already existing information in the LTM.
STM holds the information between 15 to 30 seconds and the capacity of STM is about seven items at a time. Conversely, once information enters LTM, it is retained more or less permanently and the amount of information stored in LTM is unlimited.