The set of positive integers starts {1, 2, 3, …} and there are no positive integers smaller than 1. On the other hand the set of positive real numbers has no smallest element, since for any positive real number x, the number x/2 is smaller and still a positive real. It’s not that the reals are unorderable (they are most certainly ordered), it’s that certain subsets of the reals do not necessarily contain a minimum/maximum.