whats the difference between large signal model and bias dependent linear model

whats the difference between large signal model and bias dependent linear model of transistor?
Thanks

Large signal Models take in to account the non-linearity of a device to some degree. If you change the Bias
on an Amp it will change its performance (more/less gain, different Optimal matching points). This is a Small
signal Model. Small Signal models are for devices that are used in there linear region (rule of thumb is 5-10dB
below the -1dB Compression point).