The variable t appears in differential equations and the constant T (sampling period) can also appear

Once the sampling period is chosen and with a given resolution, diverse discrete time signals can be obtained from sampling a continuous signal

The variable s appears in Laplace transforms and the variable t (continuous time) can also appear

Some discretization methods map the continuous into the discrete poles according to the theoretical definition

Difference equations are more general than differential equations

We must sample at more than ten, twenty or thirty times the highest natural frequency of a system

The variable z appears in discrete (Z) transforms and the variable s (Laplace) can also appear

The discrete Bode diagrams are different from the continuous ones because they would repeat periodically

The variable z appears in discrete (Z) transforms and the variable t (continuous time) can also appear

The discrete root locus branches are drawn the same way as continuous ones but their interpretation is different