Is the body and soul the same, and if so, why does Matthew 10:28 say, "And do not become fearful of those who kill the body but cannot kill the soul"?

The original-language for “soul” in Hebrew (ne´phesh) and Greek (psy·khe´) show it to be a person, an animal, or the life that a person or an animal enjoys.

Both ne´phesh and psy·khe´ are ALSO used to mean life as a creature, human or animal. Because servants of God have the hope of a resurrection in the event of death, they have the hope of living again as “souls,” or living creatures. That is why Jesus said that “whoever loses his soul [his life as a creature] for the sake of me and the good news will save it. Really, of what benefit is it for a man to gain the whole world and to forfeit his soul? What, really, would a man give in exchange for his soul?” (Mr 8:35-37)

So Matthew 10:28 is saying that while men can kill the body, they cannot kill the person for all time as long as he lives in God’s favor. If one of God’s servants loses their "soul", or life as a creature, it is only a temporary thing and not permanent.

Matthew 10:28 also says that God “can destroy both soul and body in Gehenna.” This is further evidence that the soul (or in Greek "psy·khe´") is NOT something that is indestructible or immortal. (See Why is the soul not immortal?; Search For Bible Truths)

For more, see:

What Happens After You Die? (Search For Bible Truths)

What really is Hell? (Search For Bible Truths)