@abhaya_jeyar the main differences in the functionality are: object recording, inspector, WF Studio “Code” for coding in groovy, different deployment options. The Pro features were also not available in Sunbird.
You can read more details in the Release notes for Lumen: https://kb.workfusion.com/display/RPAe/RPA+Express+2.0.0
Important new feature in the latest releases is also the secrets Vault.
Once the trial expires, you will not have access to the Pro features: https://kb.workfusion.com/display/RPAe/FAQ#expand-Whathappenswhenthetrialexpires
Hope it gives a clearer understanding of the differences.
Let me know if you still have any questions.