There are two types of font that films use in their openings:
Serif Fonts (for example Times and Courier)
Sans Serif Fonts (for example Ariel and Comic sans)
Serif fonts are more traditional and used for more formal occasions. Serif fonts are associated with 'Higher Class' newspapers such as the 'Times'. Serif fonts have little flicks at the tops and bottoms of letters. Serif fonts can come across as being harsh looking because of how formal they are and because of the flicks they have.
San serif fonts are not considered to be as formal as serif fonts. They are more casual and are associated with newspapers that are read by middle class people. Sans serif fonts do not have the little flicks that serif fonts do. Sans serif fonts come across as being more friendly because they are generally uses in casual situations.
EXAMPLE OF A FILM THAT USES SERIF FONT!
The poster for the film Pearl Harbor uses a serif font. As the setting of the film is during WW2, it is appropriate that an old, traditional font is used. Using only capital letters captures the audience because its bold and stands out, with the added effect of the 'flicks'.
EXAMPLE OF A FILM THAT USES SANS SERIF FONT!
The poster for the film Rocky uses a sans serif font. Again, with this poster, the use of all capitals makes the title stand out. The title is also in bold which again draws the audience in. The type of font used creates a friendly feeling to the film, again drawing the audience in.