Explain the word Lag and Latency (and some more)

[Damodred]

Hi

I need to explain the words lag and latency for a friend of mine. None of us have english as our native language, its my second and his third (spanish being second for him). Im interested in knowing story behind them as well, if they are the same thing or if Lag comes from the longer word Latency and so on! Bring all you got :) Plus a source for your knowledge if you have one!

regards
Damo

[BipolarBill]

Lag and latency are the same. The only possible difference is that lag is perceptible where latency may be so small as to only be measurable, but not felt.

[Damodred]

Thank you!