The first image does not work because the letters are blending into the background and are too simple and spaced out to read separate letters. This design looks like an eye exam instead of something you can actually read. The second design works well because the thick letter is used to contrast the graphic image. The framing of the letter and the filling in is a very smart decision and really catches the eye.
The First image places the words in an eye catching shape. This secures the attention of the audience and is a very creative way to use type. Technically it is a type within a type. The second image uses overlapping layers to contrast letters and different colors helps to differentiate between the background and overlaying text. While one of these is neater than the other I feel they both work in terms of aesthetic and uniqueness.