Can anyone here help me understand what makes the SG500X a small business switch and if there is any loss of functionality between the two models?
Small business because there are LESS functionality against Catalyst class switches. Although it may be stated in the Data Sheets what are supported it is what IS/ARE NOT MENTIONED in the Data Sheet that is the scary bit.
My personal recommendation is to read the software Release Notes because the information(s) about what features are supported and very much mapped in detail.