Presently, shortly, soon, directly are comparable when they mean after a little while or before long.
Presently carries this as its chief meaning; it is a term of rather vague implication as to the time indicated.
Shortly is often less vague as to the exact time indicated; it frequently retains one of its earlier implications of following quickly or with little delay.
Soon (see also EARLY ) implies that the thing narrated or predicted happened or will happen without much loss of time; otherwise the term is indefinite and may suggest any length of time that seems short, depending on the nature of the matter involved.
Directly often replaces its more basic sense of without delay by a value in which it is interchangeable with shortly and implies with little, or a minimum of, delay.