What is the difference between iRAT Handover and SRVCC for 4G & 5G?

[gdtelecomm]

Dear experts Any suggestion to improve 5G-4G IRAT handover performance?

We are carrying out below activities for improvement

1. NBR Flush
2. PCI audit
3. Alarm rectification
4. TAC Aaudit

Apart from these what actions can be taken to improve the same?

Thanks