I have found that while most company officers listed their men as "killed" if they were killed in battle, It is possible to have men listed as "died" that were also killed in battle.

While researching an ancestor who was listed as "died April 7 1862" (day two at Shiloh). I found that his company tended to list their battle field casualties as "died" instead of "killed".

I looked at the entire regimental casualties reported, most the companies listed their men as "killed" at such & such battle.
At least one company listed men as having died on such & such date. Nearly all these dates are dates in which a major battle took place. Many men are listed as died on either April 6th or 7th 1862. None were reported as killed at Shiloh but, of course, the Battle of Shiloh was April 6 & 7 1862, these men were obviously killed at Shiloh but appear in Lindsley Memorial Rolls & service records as having "died April 6 or 7".

I believe it is as simple as some company officers listed men as "killed" & others, perhaps later, as "died".

I later found my ancestor was listed as "Killed in Action at Shiloh" in an April 1862 newspaper.

If a man is listed as "died" on a date of a major battle he was probably killed at that battle. If he was seriously wounded at a battle & died of wounds afterward, he would most likely be listed as "died", even though he was actually mortally wounded in battle, succumbing to his wounded(s) perhaps weeks or months later.

Dates of death are important in this respect. I'm not sure if the 27th Infantry took part in the Battle of Belmont in November 1861, but it is possible that a man could have been seriously wounded at Belmont & died on Dec. 1st from his wounds.

Darron