Facebook has many different versions. They can be pretty confusing at times.
m.facebook was a simple version for mobile which didn’t come with many features. Touch. Facebook was, on the other hand, a feature-rich version of Facebook for mobile phones. In 2011, these versions collapsed into one fantastic mobile app.
d.facebook has pretty much all the functions of Facebook. However, it is devoid of the new formatting and the used space. It is pretty much a watered down version of the social media platform.
Facebook’s regular site is pretty cramped. Thus, to reduce the load, these versions were created.