Pour info :
-Designated Marksman" should not be confused with a regular sniper. United States marksmen rarely operate individually. Snipers are often deployed for specific objectives in teams consisting of snipers and observers. The marksman, however, operates as a regular member within a unit where his skills are called upon whenever the need for accurate shooting arises in the normal course of operations. While snipers are intensively trained to master fieldcraft and camouflage, these skills are not required for marksmen. There are differences in role and training that affect doctrines and equipment. Snipers rely almost exclusively on more accurate but slower-firing bolt-actionrifles,<sup>[<i>citation needed</i>]</sup> such as the M24, while a marksman can effectively use a faster-firing, but less accurate semi-automatic rifle,<sup>[<i>citation needed</i>]</sup> such as the M14. A sniper's intensive training, forward placement and surveillance duties make their role more strategic than that of a squad-level marksman. Thus, marksmen are often attached at the squad level while snipers are often attached at higher levels such as battalion (cf.: designated marksman). In short, an "SDM" or "DM" is a sniper who operates with a combat squad, while a regular sniper is deployed to gather information and eliminate specific targets.
Après au sein de l'armée française, c'est surement différent. MAIS, vu que les FS françaises s'inspirent des Tier-1 Units américaines (matériel, tactiques...) on peut imaginer que le matériel et l'organisation sont similaires.