I started researching red dots about a month ago for my Beretta Neos. I just picked up this one
http://www.amazon.com/exec/obidos/ASIN/B004DDJNOY/?tag=2ahawaii-20Main reason: it's cheap enough to take a chance and one reviewer said he has it on a 12 gauge so I figured it should handle the recoil of a .22LR easily. This red dot also has the option to change color to green, that's important because different lighting/backdrop situations make one color show up better than the other. It hasn't seen much action yet so I'll have to update later on my personal experience with it.
From what I remember of my research into red dots, there are two methods of creating the red dot image: reflex/reflector and holographic. Reflex sights project the aiming reticule (red dot) onto the viewing lens which has a mirror-like coating which then reflects the image of the reticle toward your eye. Holographic sights use a holographic reticle that is superimposed onto whatever you are looking at and don't have a mirror-like coating so it looks like you are just looking through glass.
Then there are the two shapes that red dots come in: open and tube. Open is....well open, everything is out there and a lens sticks up with the adjusting controls and aiming reticle projector behind it. Some, like EOTech, have a case around the lens so it looks a little different but still an open type. Tube types look like short scopes and have the method of projection somewhere inside the tube and the adjustment controls are on the outside. I think open or tube is just a matter of personal preference
I don't remember seeing anything about tactical red dots...I doubt it has anything to do with the reticle projection or shape. Maybe it's more durable, has more reticle shape/color options, and only comes in black, lol.
Hope that helps