Differences between SSIM v 4.7.3 and 4.8.1

Does anyone know what the main differences are between Symantec SSIM v 4.7.3 and v 4.8.1.  I am looking to replace SSIM due to it going end of life. However,I would like to know whether there are any major security improvements between the above versions.Is it worth while migrating to the latest release?