Difference in set.seed

What is the different between beta generate in first function a

f <- function(seed){
  set.seed(seed)

  beta <- matrix(rnorm(nparams), nrow=4+1, ncol=3-1)
  x <- rnorm(20,8,2)
  beta
}
f(pi)

and what is need it?

f <- function(seed){
  set.seed(seed)
  x <- rnorm(20,8,2)
  beta <- matrix(rnorm(nparams), nrow=4+1, ncol=3-1)

  beta
}

f(pi)