I made an update to that page, keeping Gunasakera’s points in there for now and then adding this:
The article by Dr. Gunasakera is very good, but out-dated for the 21st century where Buddhism is practiced in numerous places and numerous ways, including online with various forums and blogs. An updated version of the major forms Theravada takes in modern times:
A. Secular existentialist In this form people use Buddhist techniques for improving mental, psychological well being and may also use Buddhist mindfulness in a corporate setting, known as “Corporate Mindfulness.” Those who follow this form may not even meet at a temple and might meet online, in an office, or in a yoga studio. Belief in rebirth is optional and most are at least skeptical of rebirth and generally don’t follow many Buddhist practices other than meditation.
B. Traditional Temple Buddhism In this form, Buddhism is practiced at the temple and includes Refuge and Precepts ceremonies, Poya and Upsosatha day activities and other generally religious practices including blessings, funeral chanting, etc and all temple activities are performed by ordained monks and nuns.
C. Modern Theravada In this form the focus is on the Pali Canon, especially the Suttas. Those who follow this are sometimes referred to as “Suttanta.” They might still hold the Abhidhamma and Commentaries in some regard, but their main focus of study and practice are the five Nikayas of the Suttas. The members of this form are Buddhist, generally accept rebirth and simply focus on the Suttas rather than what they feel are some of the later writings and teachings.
D. Classical Theravada In this form, the Classical Theravada Buddhists hold the entire Tipitaka in highest regard along with Buddhaghosa’s Path of Purification and all the other Commentaries of the Elders in very high regard. They tend to take a more literal interpretation of the texts and strong adherence to the Vinaya.
The above is just a cursory overview and of course there can be some overlaps in one or more of the above forms showing up with some practitioners.