Suppose a bullet struck the back side of someone's head:
- He was shot in the back of his head.
- He was shot in the back of the head.
Is one of them wrong? Are they different?
Suppose a bullet struck the back side of someone's head:
Is one of them wrong? Are they different?
They mean the exact same thing, and neither is wrong. In English most of the time we use possessive determiners: these are words like 'his', 'my', or 'her'. However, sometimes we can use the definite article ('the') instead, usually when discussing parts of the body.
In some cases, the definite article is more natural. For example
The ball hit me in the knee.
sounds more natural (at least in British English) than
The ball hit me in my knee.
In other cases, 'the' sounds totally unnatural. I hurt the knee sounds incorrect; you should use
I hurt my knee.
In some cases, such as those in your question, either can be used and they both sound natural. Any differences between the two sentences you gave are very subtle and likely to be highly subjective.
Here is an article with more examples and discussion of this.