Translation:When he fell, the boy ripped his shirt.
Seems to have the same meaning to me... more words than strictly necessary but essentially the same ...in the absence of an expert explaining otherwise I would tend to report that as a possible addition to the list so the course team can consider it.
In Esperanto, when referring again to the (3rd-person) subject of a clause, you must use si (the reflexive pronoun); otherwise you're talking about another person (than the subject).
"La knabo ŝiris sian ĉemizon." -> The boy ripped his shirt (the boy and his are the same person, e.g. Billy ripped Billy's shirt).
"La knabo ŝiris lian ĉemizon." -> The boy ripped his^ shirt (the boy and his are different people, e.g. Bobby ripped Billy's shirt).
As stated above, this applies to third-person subjects: li, ŝi, ĝi, ili, oni
^This type of construction is basically unheard of in English; you'd use a name to avoid the confusion, or it might be obvious from context, but you'd never use it in isolation.