The differences between i.e. and e.g. are more significant than many think, and misuse of the two abbreviations is common. Both are abbreviations for Latin terms. The first, i.e., is short for id est, which transliterates as "that is" or "in other words." The second, e.g., stands for exempli gratia, which means "for the sake of the example" but is often translated as "for example."
One would expect to see i.e. used to clarify or put in other words something previously stated. The following is the correct usage of i.e.: "Her heart sank as the ship disappeared into the water; i.e., she was devastated." Some writers might use e.g. by mistake here, or even use the incorrect abbreviations i.g. or e.i.
Of course, writers can avoid using either abbreviation completely by substituting "in other words," for i.e. In this example, a person could write "Her heart sank as the ship disappeared into the water. In other words, she was devastated." Since people are likely to confuse i.e. and e.g., it may be wise to come up with a more simple statement.
When a writer wants to make a list of several examples to increase the reader's understanding, he or she should use e.g. For example, one might write: "He only likes games played with a bat; e.g. cricket, softball and baseball." Again this could be simplified by writing "He only likes games played with a bat, such as cricket, softball and baseball."
People often get confused because they assume i.e. means to list examples, but this is not the case. The statement, "He only likes games played with a bat; i.e., cricket, softball and baseball," is incorrect.
Occasionally, this confusion occurs because a writer wants to sound educated, and referencing Latin terms like i.e. and e.g. can make him or her sound smarter. This is a common mistake made especially by young writers; e.g. college freshman, junior high, and high school students. The misuse obviously creates the opposite of an educated feel; i.e., instructors may think the writer is not very smart.
Instead of perusing the dictionary for hugely impressive words or Latin phrases, the general standard in writing is clear, understandable English. Points should be made without excess vocabulary. Further, it is always better for a writer to use words that he can clearly define rather than to dip into words he thinks he knows the meaning of in order to impress his reader.