What is the difference between a "Feature Class" and an "SDE Feature Class"? Or a "Table" and an "SDE Table" that are hosted on the same enterprise gdb with the same direct connection. The attached screenshot below, shows my direct connection to an Oracle GDB. In the "Type" column on the right, you can see "Feature Class" and "SDE Feature Class". What is the difference between these two?

Also, in the attached ArcCatalog screenshot below are two line feature classes. Their icons are different. Why are different icons signifying?
