The different between offset press and digital print is offset press need at least to make plate(last time need film and plate) to be able to print out product while digital print no need plate/film to print out product.
This will save a lot of money if your job quantity is not much.(less than 1000 or 500).
One job after been prepared ready to print, if using offset press, they need to put plate and setup it before it can start print. (that at least take about 15min-30min depend on that worker skill and machine type) but for digital print, it can direct go to print out immediately.
There are much more thing about these 2, if want to tell out all, it will be very long story. Hope that this can give you some idea about it.