what is the deference between short bream-able and long bream-able?

Answer 1

In the context of wireless networks, I think you mean long versus short "preamble". The difference is 128 bits for a long preamble versus 56 bits for a short preamble. All 802.11 devices are required to support the long preamble and optionally support short, so long will be the default. The preamble is simply there to allow the receiving devices to sync up with the transmitting devices. The idea of the short preamble is that it is only about 1/2 the size and gives less processing overhead and improves throughput for small and numerous time sensitive frames like those carrying voice.