I wanted a difference between those states.
ECM connected : NAS Signalling is established.(SRB 1/2)
EMM registered : UE has an IP addressing, Complete EPS bearer has been established and MME knows current location of UE.
RRC_Coonected : UE Has RRC signalling bearers.(SRB 0/1)
Please explain these LTE terms in simple understanding way - RRC CONNECTED RRC IDLE ECM CONNECTED ECM IDLE