The main difference between the T$4$ slip and the T$4$ summary is:

$1.$ The T$4$ is for one calendar year only instead of a summary of all years employed

$2.$ The T$4$ summary includes information for only one employee instead of the whole company

$3.$ The T$4$ slip has a summary of all the employees in the company instead of just one employee

$4.$ The T$4$ summary is for one calendar year only instead of a summary of all years employed

$5.$ The T$4$ slip includes information for one employee only instead of a summary for the whole company