Some places a county sheriff and deputies are just a process server for the court and maintains the jail. They may or may not have any power of arrest. A person saying they are a "deputy" may mean all they do is serve court orders. They may wear a uniform or maybe not, they may be armed or not, they may have arrest powers or maybe not. The county will also have sheriff police which are the actual LE for the county. 2 completely different offices with 2 completely different roles.
Someone saying they are a sheriff's deputy is like someone saying they are an auxilary or reserve. Unless you know what the statutory role is of sheriff's deputy (same as with auxilary or reserve) they may or may not be a sworn LEO.