File contains a lot of data (Image)

For my school project I've received a few files, which 3 files are similar, but one file is containing a lot of data (5.3MB(!). These 3 files are all .jpg files, but one with a lot of data. The other two are 400KB.

The file which contains 5.3MB is viewing very weird and the other two doesnt. It's all about this file:

Does somebody know how to or does know what this could be? Stenopgraphic? Data in data file (image, jpg) or something else?

I hope someone can help me with this.