The fatter tool is a heavy duty version of the first nylon tool.
The longest tool has a beveled end for tight spaces and a notched end for small screws.
All the nylon tools are designed to not mar delicate surfaces. They are also an ideal material for use in ESD protected areas and temperature resistant so will not melt when soldering. They are made in the USA for superior quality.
The flat metal one is what many professionals use to open iPhones, iPads, and cases that require more leverage or a sharper tip. It's handy for cell phones, laptops, LCD screens, and other plastic electronics especially where the LCD cover is glued to the screen. I've also been able to open some plastic AC/DC power supplies with it. This is made of metal so it is stronger than the plastic tools, but you have to be more aware of possible scratching. Approx 4 3/4" long.
The dental style metal tool is a more delicate metal tool made for the professional. The different ends will handle many repair jobs and the handle is designed for comfort and grip.