Choosing between practical ("sensible") and practicable ("possible") often depends on context.

Quiz time! Choose your words:

Luxury gifts are out this Christmas – with practical/practicable presents now topping most people's wish lists.

Health Amendment Act 2007 required councils to take all practical/practicable steps to ensure drinking water complied with drinking water standards.

The Torah contains 613 commandments, many of which we call ritual because they don't fulfill a practical/practicable or moral purpose.

In the first sentence, the presents on people's wish lists are sensible or reasonable. They're practical. Here's another example:

The problem with personal budgets is practical, not ideological.

The second sentence refers to steps that can actually be put into practice, steps that are achievable. They're practicable:

He failed to take all practicable steps to ensure his actions did not cause harm to any other persons.

‎The third quiz sentence talks about three types of commandments: those concerned with religious ceremonies (ritual), those concerned with a sense of right and wrong (moral), and those concerned with things able to be put to use. That last group was labeled practical in the original sentence. But if those commandments, such as returning lost objects, are ones that we can put into use, aren't they also practicable, commandments that are feasible? In a word: sometimes. Context can be everything.

When faced with a choice between practical and practicable, look at the context around the word. Do you mean to say that a thing is sensible? Choose practical. Do you want to say it is possible? Choose practicable. Out of context, sometimes either word will do.