Character oriented protocols and bit-oriented protocols

1. Can you please describe the principle of character oriented protocols and bit oriented protocols?

2. Also by drawing a table compare the frame formats of the following modem protocols Xmodem, Zmodem, RTS/cts, XON.xoff, echoplex and what can the advantages and disadvantages possibly be?
Dear Joe,

Are you planning to set up a remote access server or dial-up solution (with modem pool) for your company? As for the advantages of bit oriented protocols vs. char (byte) oriented protocols - bit oriented protocols support full duplex mode, are more reliable, and more efficient than byte oriented protocol.