Flow Control: - 
In communications, the process of adjusting the flow of 
data from one device to another to ensure that the 
receiving device can handle all of the incoming data. This 
is particularly important where the sending device is 
capable of sending data much faster than the receiving 
device can receive it. 

Error Control: - 
Error control is a method that can be used to recover the 
corrupted data whenever possible. There are two basic types 
of  error control which are backward error control and 
forward error control. In backward error control, the data 
is encoded so that the encoded data contains additional 
redundant information which is used to detect the corrupted 
blocks of data that must be resent. On the contrary, in 
forward error control (FEQ), the data is encoded so that it 
contains enough redundant information to recover from some 
communications errors.