In French, we use the term informatique for computer science, as the latter can be seen as the science that studies the treatment of information. Is informatics a synonym for computer science? If not, what is the difference?
It depends — different people use the words in different ways. Don't assume any particular nuance from the use of computer science vs. informatics without clarifying context.
Computer science is more commonly described among its practitioners as the science of computation than the science of information. While laypeople cannot be expected to understand what “science of computation” is, the term computer science is not nearly as prone to the interpretation “knowing how to fix your computer” like the word informatique is in French, due to containing the word science.
Informatics, on the contrary, is usually the science of information, often (but not always) with a focus on its social implications. The term information science also gets some use; it has a more consensual meaning covering how societies process information.
Just to add to the confusion, information theory has a precise meaning; it is the branch of theoretical computer science that studies mathematical models of information with a quantitative perspective.
Informatics is not a very common word and does not have a single widely-agreed meaning. Nuances and trends are still evolving. Wikipedia currently gives a particular meaning in its introduction section:
Certainly, by some definitions, everything that is listed here could be considered aspects of applied computer science. For example, human-computer interaction is often classified as bridging computer science with sociology and other fields. For example (more or less random), the CMU HCI Institute defines itself as “headquartered within the School of Computer Science, [but representing] a broad spectrum of the CMU campus including the College of Humanities and Social Sciences, Tepper School of Business, College of Fine Arts, Carnegie Institute of Technology, Software Engineering Institute, as well as the School of Computer Science.”
The history section and talk page provide differing perspectives on the word. It started out as a translation of the German Informatik and French informatique (which cover a wide range of meanings including computer science and information technology).
Wars (at least flame wars) have been fought over which term should apply to which concept, and whether X is a subdiscipline of Y or an overlapping discipline, etc. Tread with care, and define your terms.
No, they are not the same, though they do have much in common.
Informatics is the study of information and its processing. This need not involve computers; for example, our brains perform massive amounts of information processing every day. US universities (according to a cursory web search) often treat informatics as the study of the intersection of computing and society (1, 2, 3).
Computer science is the study of mechanical computation and its applications. On the informatics page, Wikipedia lists computer science as a sub-discipline of informatics. CS, as many a joke about the field hints, is strictly technological and doesn't study society or its interactions with technology.
Just in case you are looking to obtain equivalence for your qualification elsewhere, you may be interested in matching your own skills to what's covered in job descriptions in the disciplines we are now calling Information and Communications Technology (ICT).