what you use depends entirely on what you are trying to accomplish. is this an antenna switch to change antennas on a receiver, or a transmitter? is this a T/R switch to switch one antenna between a transmitter and receiver? your question is about as specific as "what's the difference between a duck?" or "i need to use a capacitor in a circuit, what kind should i use?".... as you can see there is no answer to the first question, and the second question is so vague, it can't be answered (i.e. what circuit?, where in a circuit? what is the capacitor being used for?)