What is the difference between the names "1-propanol" and "propan-1-ol?"
There is no difference, but propan-1-ol is the preferred name.
In the "old" IUPAC system, the correct name was 1-propanol.
But IUPAC now recommends that all locants (the numbers that locate a substituent or functional group on the chain) be as close as possible to the group they locate.
Thus, the "1" should come just before the "ol".
This makes the naming more consistent.
For example, in 3-ethyl-2-methylhexan-1-ol, the numbers come just before the groups they locate.
In 3-ethyl-2-methyl-1-hexanol, you have to do a little thinking to recognize that the "1" goes with the "ol".
1-Propanol is allowed, but propan-1-ol is the preferred name.