The difference between them is whether they command categorically or hypothetically. To command categorically is to command absolutely, universallv and without exception. To command hypothetically is to command only on the meeting of certain conditions. Hypothetical Imperatives Kant knows or takes it for granted as being obvious that ought judgments of a certain sort are possible. That such a type of ought judgment is possible lies in the fact that there are things people want and, in wanting them, there are things that one ought to do to get their goals.
Hypothetical imperatives are rules one needs to follow for the attainment of some end.
Following the hypothetical imperative is good solely as a means to some end. Notice that hypothetical imperatives are connected with means-end rationality. These rules only apply to you if you want the end they help you attain. If you want to join the swim team, learn the butterfly stroke. Suppose I am sitting in a very hot office.