HIeugene1973
Greetings, you are seeing this difference because the SRX300 uses the enhanced layer 2 software and you SRX240 does not
ELS devices use the "IRB interface" as the SVI, here is a list of devices that are ELS as well, any other device that is not in this list will be considered as a legacy device hence they will use the "vlan interface" as their SVI
SRX300
Junos OS 15.1X49-D40
SRX320
Junos OS 15.1X49-D40
SRX340
Junos OS 15.1X49-D40
SRX345
Junos OS 15.1X49-D40
SRX550 HM
Junos OS 15.1X49-D40
SRX4100
Junos OS 15.1X49-D65
SRX4200
Junos OS 15.1X49-D65
SRX5400
Junos OS 15.1X49-D10
SRX5600
Junos OS 15.1X49-D10
SRX5800
Junos OS 15.1X49-D10
If this solves your problem, please mark this post as "Accepted Solution" so we can help others too \:)/
Regards,
Lil Dexx JNCIE-ENT#863, 3X JNCIP-[SP-ENT-DC], 4X JNCIA [cloud-DevOps-Junos-Design], Champions Ingenius, SSYB