Emmauel Kant describes public use as always free. The public use of reason is not restricted by work/official duties or other people. A persons public reason is their ability to express their views with free speech. Private reason is “narrowly restricted” by a persons official duties. Meaning you can not speak nor disagree with the establishment you work for. In a nutshell public reason is free, private reason has restrictions to keep social order in tact. With private reason a preacher cannot preach against the religion he or she is preaching or his or her church. Same as a president cannot speak against his or her country. 
Today public and private are used in companies, schools, finances, goods, etc. Today private is used in a way of determining something better and more exclusive. For example, private school, although it may not be better than public school it is still deemed more exclusive because it is private. There are two definitions for private in the dictionary but the one that moreover relates to the topic is, belonging to or for the use of one particular person or group of people only. Public has two definitions, first being of or concerning the people as a whole. The second definition is done, perceived or existing in open view. The distinction of private and public used by Kant are different but not too different than the way we use today. Today your private reasons are kept private and not expressed at your work place, just like how during Kant’s period, you did not argue you went with your obligations of your official duties. If you are to speak against your boss or a company you work at you would get fired. Just how in turn, public reason although now may be more limited because everyone sees everything it is still free. The only difference in public reason between now and Kant’s period is risk. There were always repercussions for speaking freely, but now they come quicker and sometimes a lot harder because of the day and age we are in. In all, the distinction between Kant’s period and today on the terms “private” and “public” are not too different but not completely the same.