The biggest differences between the Guild and other websites is, in my opinion, the intra-thread tabs. Threads created in the roleplaying subforums (Free, Casual, Advanced, One-on-One, Tabletop and Nation) all have an IC (in character), OOC (out of character) and Character (for submitted character/nation sheets) tab. This saves space and means every roleplay only needs to have one thread. 

Unlike some other websites, roleplays are divided by quality instead of genre. Beneath the name of every subforum is a little description that tells you what kind of writing quality can be expected of you. 

Other than that, it's a pretty regular forum. Mahz (the admin) coded it from scratch, so it doesn't look like any kind of vBulletin or php-based forum you may be used to, but it has most of the same features. 

Hit me up if you have any more questions, [@Lavi Lavela]. Welcome to the Guild. :rock

EDIT: I also suggest reading this guide: http://www.roleplayerguild.com/topics/4958-a-new-users-guide-to-the-guild/ooc