Last Friday Night- Katy Perry
This opening contains font that represents the genre of the song well. It is bright, large and has a cartoon-like look to it. This hints that the video will also be like this. The positioning on the text is central but is also displayed in one long tracking shot in the background.
G.U.Y- Lady Gaga
This opening contains iconic plain, bold and extremely large text. The font is completely white having connotations with holiness, purity and innocence which are themes often reflected in the artist's videos. The backgrounds of these credits are either plain to emphasise the text or do not focus on anything in particular unlike Last Friday Night. I believe these credits are less of an introduction to the video and more of a branding on the product for the artist. EG: It is common to see the "Haus of Gaga" phrase in the artist's videos.