IMHO, "How many passengers? => 150" is very different from "How many souls? => 156" ... passengers necessarily may be interpreted as "people who paid for seats"

IMHO, "How many passengers? => 150" is very different from "How many souls? => 156" ... passengers necessarily may be interpreted as "people who paid for seats" and not include the 2 pilots and 4 flight attendants [as an example]. "A plane went down with 150 passengers, all 156 souls aboard were lost." I guess "soul" is the universal term for "living human", regardless of their job, role, lot in life, etc.