Layer 2 services on the SRX300 series are all using the new ELS (enhanced layer 2 services). Likely your older SRX220 has the original layer 2 configuration.
You can run your current configuration through the ELS translator to see if it recognizes it as an older config and gives you a converted one.
https://www.juniper.net/customers/support/configtools/elstranslator/