pasteurisation vs. pasteurization

English spelling: pasteurisation
American spelling: pasteurization
This differently spelled name for the process that slows microbial growth in milk and other foods is derived from the name of the French chemist and microbiologists Louis Pasteur.

Suggested Reading
Bryn Nelson: The Lingering Heat over Pasteurized Milk. Chemical Heritage, Spring 2009, Volume 27, Number 1, pages 26 to 31.
Internet: www.chemheritage.org/pubs/magazine/feature_pasteurization_p1.html

liquefy or liquify

The words liquefy and liquify are different spellings of a verb with the following meaning: to turn a material into the liquid state. Common derivatives:
liquefied, liquified; liquefying, liquifying; liquefication, liquification.
These words are frequently used in the physics, chemistry, and engineering context.

behaviour vs. behavior

English spelling: behaviour
American spelling: behavior
The difference in spelling carries over to derived words and phrases. For example:
behavioural scientist vs. behavioral scientist.