The difference between a teaser trailer and a theatrical trailer

When advertising a film, we will usually see a teaser trailer that will later be followed by a theatrical trailer.

The teaser trailer is usually meant to entice the audience and create hype for the production without revealing too much information. The idea is to create a sense of intruige to work alongside the advertising campaign
Likewise, a theatrical trailer is usually meant to explain the plot and general themes of the film, allowing the person watching to make an informed descision as to if they want to watch the film or not.

Common themes that the teaser trailer will have in comparrison to the theatrical trailer is the use much faster music, much shorter shots and generally the trailer as a whole will be smaller.
Whilst both the theatrical and the teaser trailer will often use a large title as part of the usual design, the teaser trailer will usually have a much bigger emphasis on the title (at least in how it stays on longer than most shots)