In recent times there have been a rapidly increasing number of sustainable buildings entering the global real estate market. Many of these buildings differ considerably with respect to their sustainable features from a design and/or performance basis, although a wide range of sustainable building assessment tools are now promoted and readily available throughout the world. Unfortunately many of these tools differ considerably with regards to what they actually assess, how they operate and whether they can be compared directly with assessment tools from other countries. Some global rating tools require a complex series of analytical steps whilst others are conducted on-line via a questionnaire approach and are also substantially less expensive. This paper is based on the last year paper ìInternational Comparison of Global Sustainability Toolsî and examines their characteristics and differences. As the previous paper showed the market for rating tools is worldwide growing. Most importantly the focus is placed on which tools from different countries can be directly compared with each other i.e. is a five star building with one rating system directly comparable with a four star rating another rating system? And a second focus should have a look on the trends in this market i.e. which rating system is the most popular or which tool is the cheapest one? The results of this paper are designed to lessen some of the confusion that accompanies assessment tools for sustainable buildings, which in turn will assist investors, developers, tenants and government bodies to make informed decisions about green buildings. In addition it is envisaged that removing some of the uncertainty associated with sustainable buildings will increase the transparency for stakeholders and assist them to embrace sustainable buildings with more confidence.