PIE vs Manchester Coding
Manchester encoding is designed so that the percentage of time that the signal is in one state is exactly equal to the percentage of time that the signal is in the other state. This means that there is no accumulating bias of the average level of the signal while it is transferred through what ever communications medium is in use. Pulse Interval Encoding on the other hand does not have this property.

The average level of zero for signals being sent through a channel is important for any medium that cannot be DC coupled or for where an accumulating bias toward one state or the other would would cause the receivers used in the path to saturate toward one side or the other. 

Manchester encoding extracts a price for its use because it requires two times the bandwidth of the actual data rate being sent through the communications channel. There are a number of other serial type protocols that help to lower this "cost" by being designed for less than the 2X bandwidth requirement. The various schemes add compensating patterns to the data flow that so that the average level of the signal stays at zero over a longer period of time than the one bit interval used by Manchester. 

Pulse interval encoding is commonly used for IR encoding with remote controls. They get by with this at the receiving end in one of two ways. The messages sent are short compared to the repeat time between messages which allows the receiver to relax to the center of its detection range between messages. And some IR encoding protocols include both the true and inverted copies of the data in the message packet sent which helps to average the receiver. It is interesting to note here that Manchester encoding is actually used in some IR remote protocols including the Philips RC5 encoding.