What's the difference between class-based exceptions and classic exception?

Hi buddies,

I was learning the new class-based exception handling, a question suddently jumped in my brain:what's the difference between the new concept and the old exception concept EXCEPTIONS

*\ conversion_error = 1

*\ file_open_error = 2

*\ file_read_error = 3

*\ invalid_type = 4

*\ no_batch = 5

*\ unknown_error = 6

*\ invalid_table_width = 7

*\ gui_refuse_filetransfer = 8

*\ customer_error = 9

*\ OTHERS = 10.

?