What is the difference between the ELF Visibility Values STV_INTERNAL and STV_HIDDEN?

I was trying to understand Visibility values in ELF file , and I couldn't Understand the difference between STV_HIDDEN and STV_INTERNAL . After some reseach I found that this may be related to how symbols are exported in symbol table , am not sure whether that is correct or not but if some one explain the story behind the difference it will be helpful for me . Possible Duplicate : https://unix.stackexchange.com/questions/472660/what-are-difference-between-the-elf-symbol-visibility-levels But from the answer there I still couldn't get the difference , perhaps more explaination may help me . Thanks