How does the standard normal distribution differ from the t-distribution?
The normal distribution and the t-distribution are both
symmetric bell-shaped continuous probability distribution
functions. The t-distribution has heavier tails: the probability of
observations further from the mean is greater than for the normal
distribution.
There are other differences in terms of when it is appropriate
to use them.
Finally, the standard normal distribution is a special case of a
normal distribution such that the mean is 0 and the standard
deviation is 1.