What is the difference between a teaser trailer and a main theatrical trailer?

 Theatrical trailers are normally longer than teaser trailers because they are usually shown in the cinema to audiences so it engages them more and makes them want to view the film more. They are usually only longer by about a minute or two but in trailer terms, that is a fairly long time. The Theatrical trailer will show much more of the plot and story line than the teaser because a teaser is only there to give little snippets and get the audience excited and wanting to see more. Theatrical trailers are normally released near the time of a film being released because it is another chance to get the audience engaged before being released and is usually the thing which gives a film its premature publicity. Although most big films have teaser trailers, it is not something which all films have, this is for multiple reasons, the main ones being time and money, or just the fact that there isn't really any necessity. There is no clear line which determines which type of trailer is more effective because they both serve a different purpose and in my opinion, including both of these types of trailer is the method which engages the audience the most and gets them hyped up to seeing a film, because after seeing a teaser trailer, there is always the want to see more and a theatrical trailer serves this purpose.