Basically it is the same as power in kW ie 10kva = 10 kW. There are differences with respect to expected and actual power output but are only meaningful to electrical engineers.
Examples of the differences mentioned by Scotstone can be determined here
It shows that a for a given KVA rating, you could only get 80 percent power output in actual KW.
Put the other way, in some cases, for a required KW load, you might need a 25 percent higher KVA rating.