What is the difference between the abbreviations i.e. and e.g.?

Because I ran into a use of e. g. that didn't look right, so I went and looked it up. From Merriam-Webster:

The most looked up abbreviations in our online dictionary are i.e. and e.g., probably because they are often confused for one another.

Both of these are abbreviations of Latin expressions: i.e. stands for id est, which means “that is” in Latin. It introduces a rewording or a clarification of a statement that has just been made or of a word that has just been used, such as:

The cough may last for a short period of time—i.e., three to five days.

E.g. stands for exempli gratia in Latin, which means “for example.” It introduces one or more examples that illustrate something stated, such as:

Submit a sample of academic writing—e.g., a dissertation chapter.

Because their usage can seem similar, these abbreviations are often confused. One trick to keeping them straight is to remember that i.e. and that is both share an i and that example and e.g. both share an e.

You can also try substituting the English for the abbreviation to check:

The cough may last for a short period of time—that is, three to five days.

Submit a sample of academic writing—for example, a dissertation chapter.

I was correct in my thinking, the usage I ran across was also correct, it was just odd. I usually think of i. e. as meaning 'in other words'.