What is the difference between practice and practise?

Do not confuse “practice” with “practise”. They sound the same and even look similar (except that one is spelled with a “c” and the other with a “s”) but their meanings are different. The word “practice” is a noun, it refers to an act itself, not who is doing it. On the other hand, practise is a verb meaning ‘do something repeatedly to improve one skill’. It is a systematic training by multiple repetitions (rehearsing a behavior or engaging in an activity several times repeatedly) in order to improve or mastering that skill. To put this much simply, practise is a verb (doing word) and practice a noun (thing).

Source: http://tellmewhyfacts.com/2008/06/what-is-difference-between-practice-and.html

Practice and Practise

There is often confusion over the words practice and practise. In order to understand which to use, you must know the difference between a noun and a verb. This is because practice is a noun, but practise is a verb.

If you follow US convention, you don’t need to worry about this as you can use practice for both noun and verb. If you follow UK convention and you’re not sure how to spot nouns and verbs, there are tricks you can use to help you. See Hot Tip right.)

You need more practice.     (“practice” – noun)
(Using the trick shown in the Hot Tip: “You need more preparation.” This sounds
okay. Therefore, practice is correct.)

–  You should practise more.   (“practise” – verb)
(Using the trick shown in the Hot Tip: “You should prepare more.” This sounds okay.
Therefore,practise is correct.)

Try using the word preparation (or lessons) instead of practice. If the sentence still makes sense, then practice is almost certainly correct. (This trick works because practice is a noun, just like the words preparation and lessons.)

Try using the verb to prepare (in its various forms, e.g., preparing, prepared, prepares) instead of practise. If the sentence still makes sense, then practise is almost certainly correct. However, if you find yourself trying to use preparation, then you should be using practice because both are nouns.
(This trick works because to practise is a verb, just like to prepare.)NO CONFUSION
There should be no confusion with practising or practised. These are always verbs.

Source: http://grammar-monster.com/easily_confused/practice_practise.htm