What is the difference between word Utilisation and Utilization they mean same so how both are differentiated?

You are absolutely right! "Utilization" and "utilisation" are essentially synonyms. They both refer to the act of putting something to use or the state of being used.

There's really no significant difference in meaning.

However, "utilization" is the more common spelling in American English, while "utilisation" is more common in British English.

So, the choice between the two depends on the context and the target audience.

If you are writing for a global audience or are unsure of the reader's location, "utilization" is probably the safer choice.