These terms and their derived forms (“digitalize” and “digitize”) refer to the process of converting audio or visual information into numbers so that it can be transmitted, then converting it back to its original form.
The adjective “numeric” is a learned derivative of the Latin numerus, meaning “number.” It appeared in French in the early 17th century and seems perfectly suited to expressing the concept in our language. The English word for “chiffre” is digit, from the Latin digitus, meaning “finger.” The reason seems obvious: we count to ten on our fingers. It was therefore only natural that “digital” came to be preferred in this sense across the Channel and the Atlantic.
The outsized role Americans played in the development of computing and related technologies explains why the word “digital” has entered many languages, including ours. Should we follow the Académie française or the Twitter account @NumeriqueBordel, or simply yield to a certain Anglophile snobbery? The choice is yours. In any event, these two words cannot coexist forever as perfect synonyms. Either one will displace the other (as “pullover” did “chandail”), or the terms will acquire slightly different meanings, as “function” and “map” do in mathematics. Yet the adjective “digital” is perfectly good French: it describes anything relating to the fingers (as the expression “empreinte digitale” attests). The advent of touchscreens may restore the adjective to its full meaning!