Information graphics are visual representations of information, data or knowledge often used to support information, strengthen it and present it within a sensitive context.
They are specific, context-sensitive and often times hand-crafted.
Data visualizations are visual displays of measured quantities by means of the combined use of a coordination system, points, lines, shapes, digits, letters quantified by visual attributes.
They are general, context-free and often times created automatically.
Both can be static, animated or interactive.
So, I think the difference is more about the objective. Information graphics are used to tell a story or answer a question. Data visualizations are used to let the user find his own story or answer.