I'm not really sure where you are shopping. I picked up my Varmint a few months ago for a sliver less than $450.00 and picked up my Tacticool for just a shade over $500. There was about a $60 price differential. The varmint came with rings and an extra mag. The Tacticool had no accessories.
That Tacticool comes with a threaded barrel and composite stock, so I guess that would be the difference in price.
Not really going to go into all the differences between the two models. You can do that on the CZ webpage. There are not that many. I will say I wasn't pleased with the Varmint's trigger out of the box. It was heavy and gritty and no amount of adjustment or monkeying with it seemed to improve it much. After getting on the Tacticool trigger, I assume the Varmint trigger wasn't intentionally set up so cruddy, as the Tacticool trigger was fine out of the box and is almost as crisp and light as the Timney 2# I opted to install in the Varmint.
The reason I wanted the Tacticool was I wanted something shorter for my suppressor and the more substantial stock for my Varmint.
So now I have a handy little rifle for my suppressor and a more elemental heavy .22. Pleased with both.
Before:
After: