The verbs start and launch are both used to talk about setting something into motion, but launch implies movement of a bolder or more sudden nature. Material objects that are launched (rockets, missiles) are sent out with some force. This sense of blasting or bursting forth is carried over into the launching of things immaterial, such as campaigns, initiatives, or careers. Additionally, a person who launches into speech or action plunges right in, again suggesting a boldness or forcefulness that would be lost if they were to start to speak instead.
The verb establish implies making something new more stable and enduring. The verb enact also creates permanence, but it does so primarily via legislation. To enact something is to make it into law—in fact, bills introduced by Congress begin with the phrase “Be it enacted.” Drawing on a different sense of act, enact can also mean to represent on or as on the stage, as in a performer who is enacting Hamlet. But in the saga of the English language, this sense plays merely a supporting role.
The verbs get and obtain both imply gaining possession of something. But obtain suggests more effort toward that end. For instance, you might hear of information or permission being obtained after having been sought out or requested. This is not always the case with the verb get, which sometimes implies no effort. For instance, that lucky friend who will get the perfect birthday present from you may be blissfully unaware of how difficult it was to obtain!