The primary difference between T1 and E1 signaling is the data rate.  T1 has a data rate of 1.544mbps and E1 has a data rate of 2.048mbps.  While the line rate is the same, E1 signals use more channels which is what accounts for the different overall data rate.  With respect to the monitoring ports, T1 signals use a 432 ohm resistor for the electrical isolation and the E1 signals use a 536 ohm resistor.  Therefore, using a T1 jack for an E1 signal may have an impact on the monitoring port and vice versa.