What is the difference?
From Dictionary.com:
Usage Note: It is easy to confuse practicable and practical because they look so much alike and overlap in meaning. Practicable means feasible as well as usable, and it cannot be applied to persons. Practical has at least eight meanings, including the sense capable of being put into effect, useful, wherein the confusion with practicable arises. But there is a subtle distinction between these words that is worth keeping. Someone with a practical knowledge of French may be able to order coffee in a caf, though it may not be practicable to learn the language of every country in Europe.
According to my dictionary:
“Practicable” describes that which can be put into effect.
“Practical” describes that which is also sensible and worthwhile.
Not much help.
Courtesy of my “American Heritage Dictionary” CD:
Practicable means feasible as well as usable and hence overlaps in meaning to some extent with practical, which can mean useful. However, practicable does not share any other senses with practical.
I’ve always thought of “practicable” as being able to be put into practice. It may or may not be practical to do so.
It is subtle but there is practicably no difference between the two words.
Of course there is; it may be practicable to use pen, ink and vellum to produce specifications. But it is not practical to do so.
I agree with Lynn. (practicable = being able to be put into practice) Specifiers often use practic[e]able as in "Apply coating by brush, roller or other practicable method to achieve smooth finish. Specifiers seldom use practical; its up to the contractor to figure out if the practicable method of spraying the coating is practical for the project.
Lynn and George expressed the meanings effectively - in my opinion there is an important difference.