I recently got a set of the Original T-boots (with stud closures) and really like them for schooling. As I understand it, the main difference between my boots and the EXP2 is the outer covering.
The originals have a no-gloss finish and are mostly covered in the "Dyno-Hide", a rough carbon fiber like material that seems to be super tough.
The EXP2 have a glossier, leather look finish. I imagine these might be more appropriate for show as you could more easily wipe the dust off before you head in the ring. My originals will always be a dull dark grey color, which is fine by me for schooling, but I wouldn't use them in the EQ ring.
As a representative for EquiFit I wanted to personally answer your question in regards to the difference between the EquiFit T-Boots.
The difference between the T-Boot Original and the T-Boot EXP II is just the materials. All of our materials and products are hand-crafted in the USA at our manufacturing facility in Dedham, MA allowing for quality assurance throughout the production process.
The quality of the T-Boot series is unsurpassed. The EquiFit T-Boot series is the first line of boots to combine an advanced, custom fit with interchangeable, shock absorbing liners that can be paired with a variety of outer shells to meet each rider's needs.
The T-Boot Original™ is made from a EVA outer shell, that is lightweight, pliable and shock absorbing. It also features a reinforced strike zone that is made from RhinoTek™.
The T-Boot EXP II™ is made from a leather-like, durable, polyurethane shell. Offering superior protection, comfort and support.
All of the EquiFit T-Boots feature advanced T-Foam™ technology to disperse pressure points, provide maximum hold up, and reduce rubs like no other material. T-Boot liners are removable, breathable and Neoprene-free. This aids in the prevention of skin irritations, allergies, scratches and over-heating. All T-Boots offer maximum support, comfort and protection.
Please feel free to contact me directly if you have any further questions.