Anyone looking to remember the difference: "id est" (that is) vs "exemplī grātiā" (for the sake of an example). You use the first to clarify meaning, and the second to begin a non-exhaustive list of examples.

What matters is ultimately if you can convey your ideas, so using the wrong term is fine when people can still figure out what you meant. But it's still a good idea to learn the difference, because there will be times when mixing up "i.e." and "e.g." will create ambiguity or misunderstanding.

The best idea is maybe to use "for example" or "that is to say". The former could be abbreviated to "f.ex." like in Norwegian, and the latter could be abbreviated "t.i.t.s."

...Alright, on second thought maybe don't abbreviate that one.

In any case, the Wikipedia Manual of Style recommends avoiding use of "e.g." and "i.e." in regular running text altogether, saying that these abbreviations are better fit for parentheticals, quotations, citations, tables, and lists. This is because there is no word or character limit on Wikipedia, nor is there on Tumblr, and so the language is more clear when abbreviations are avoided. Even when someone is using "i.e." and "e.g." in the prescribed way, that doesn't guarantee that the reader knows the distinction.