What is the difference in the meanings of the following two sentences?
1) He may have missed the train.
2) He may have missed his train.
Does "his train" in 2) mean the train he usually takes to go to school or work?
If someone was visiting you by a particular train and he doesn't arrive by expected time you can say he may have missed the train. Here the refers to a particular train and possibly well known to people around you.
If that person was going to come by just any train (like if there are several trains plying between source and destination) and not any particular train then you can say he may have missed his train.