What's the difference between "preposition" and "postposition" compared to "circumposition"?

Solution 1:

Prepositions, postpositions, and circumpositions are three types of adpositions defined by where they occur relative to the element they govern:

Prepositions are placed before the element they govern: “on the ground”, “without any help”, etc. English employs mainly prepositions. (For this reason, some people use the term ‘preposition’ to refer to all kinds of adpositions, especially in English.)

Postpositions are placed after the element they govern: “his claims notwithstanding”, “the whole night through”, etc. English has a few of these, but they are limited in both number and use. Other languages use them more prolifically or, like Japanese, exclusively (“アメリカに” Amerika-ni ‘in America’, “二時から八時まで” niji-kara hachiji-made ‘from two o’clock till eight o’clock’).

Circumpositions consist of two parts: one placed before the element they govern, and one placed after it: “from now on”, etc. These are quite rare in English (I can’t think of any other examples than this one, taken from Wikipedia), though they are quite common in languages that frequently use both prepositions and postpositions, such as Chinese.

The Wikipedia page linked to above has quite a thorough explanation of adpositions.

Solution 2:

Regarding officiality, the wikipedia article Adposition suggests that indeed “Some linguists use the word "preposition" instead of "adposition" for all three cases”, the three cases being prepositions, postpositions, and circumpositions.

Note that a circumposition has two parts and surrounds the complement, ie has one part per side.

The terms preposition, postposition, circumposition, and their hypernym adposition are in use in linguistics, where technical terms are needed for brief but accurate reference.