Most users stick to the "Easy Flash" tab because it handles the heavy lifting—downloading the correct IPSW, verifying the SHSH blobs, and executing the restore. Pro Flash strips away this automation.
: The macOS version of 3uTools is currently limited and does not support the Pro Flash feature; you must use a Windows environment for these advanced functions. pro flash 3utools
When you enter the Pro Flash interface, you are presented with several options and buttons. Here is what they mean: Most users stick to the "Easy Flash" tab