It depend very much on the context. Ancient documents are notorious for preposterous and absurd figures. For example Persians didn't march to Greece with millions of soldiers. Even their empire didn't have that many. Medieval battle records are equally dubious.
Only in more modern times 100.000 men came to mean 100.000 men, instead of 'many' or 'very many' men. In our day and time it works the other way around. The Chinese as well as the Germans and the Japanese aren't exactly proud about their horrendous killing records. Something the ancients would be very proud to chisel in stone. Pompey the great build a trophy on a pass in the Pyrenees with the number of people killed and captured during his tenure in Spain.
'Loosing xxx men' and 'xxx men in casualties' are semantics. Loosing can mean both killed and injured. Casualties is killed only. It's not common, certainly not for very large battles, to record the number of wounded. Wikipedia records during the Battle of Verdun both the number of wounded and killed for each side. Elsewhere I often read the number of victims in a certain battle, not specified how many were wounded.