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

Teaser trailers are normally released very early in the production of a film; it is simply to make the audience aware that the film is being released and to make them look further into it. Teaser trailers do not often explain the narrative and often try to literally tease the audience into wanting to know more about the film.

Normal trailers are released once production has finished, this kind of trailer is used to tempt the audience into seeing the film by explaining the film narrative to narrow down the target audience.