The Ruger Mark Series pistols have always had a broad spectrum of features within the line up, so it would really be exhaustive to go through all of them, but there are some general differences, and a few truths to be realized.
Truth: Throw a red dot or scope on top and a bench underneath, and you'll struggle to find any difference in raw accuracy potential for ANY of them. However, the contributions of sight radius, sight type, and balance to off hand precision are all real. The longer, heavier barrel models with the patridge sights will generally outshoot the shorter, lighter barrels with dovetail sights.
Truth: All of them have the same internals, so they all have the same trigger quality out of the box. There's nothing really WRONG with their trigger, but they could be "more right." The Volquartsen sear & disconnector and a Clark or Tandemkross hammer bushing will bring you up to a VERY happy place with a Ruger Mark IV trigger, without spending an arm and a leg. They're serviceable without upgrade, but you'll drop less points by adding these parts.
Truth: The aesthetic options for the 22/45, 22/45 Lite, Standard, Hunter, Competition, & Tactical are all very different, and aesthetic preferences are always subjective. I love the Competition & Standard (tapered) models, my wife loves the Hunters and the 22/45 Lites.
Truth: There are 3 sight options for the Mark Series pistols, currently, some lending themselves better to precision shooting than others.
Truth: There's a pretty surprising spectrum in how the different models will balance in hand. The Lite and Standard/Taper models, especially the shorter 4 3/4" models, will obviously handle more lightly up front than the heavy barrel models. The Aluminum framed blued models" will be a bit lighter in the tail than the stainless models.
Differences: The Standards use a windage driftable rear sight, but are otherwise relatively poor sights. The Hunters use a fiber optic front sight, with a V-notch rear sight, offering a fast and highly visible, yet relatively imprecise sight picture. The Competition, 22/45, both Tacticals, and Target model all use a square notch blade in a fully adjustable rear sight and a patridge front blade, offering the greatest degree of precision in the fleet, although lacking the visibility and speed of the Hunter's "lollipop" sight picture.
Differences: The 22/45's claim to fame was the similarity to the 1911 frame, and even the opportunity to utilize 1911 grip panels (however modified now with the Mark IV evolution). It has a very different grip in hand than the Mark IV, and a different balance, especially in the Lite version. Ruger HAS, however, rectified the differences in the controls present for the Mark III versions, so now the bolt stop lever is the same for both models. I'm hard pressed to say they "handle like a 1911," since the safety is different, the balance very different, the bolt stop lever is different, bolt instead of slide, fixed instead of reciprocating sights, etc etc... But the grip shape is familiar to the 1911.
Differences: The Hunter is available with a semi-wrap around grip, and the Competition comes with a right handed thumbrest shingle (although it's still not as comfortable as the Mark II version). The rest of the Mark IV's are really the same profile shingles, and the 22/45's are all the same 1911 style. I shoot predominantly left handed, so I have to face buying new grips with every iteration of the Competition I buy. Some folks find the wrap around grip to be overly large (as the Mark series grips are already large).
Personally, I grew up on a Standard/Tapered for my field work, and slab sided Competitions for my precision work. I have Mark II, III, and now IV's in both of these versions. My wife has the Hunter in III and IV, a Lite in III, and has her eye on a new Lite IV. I have a Government/Target II and another in IV. All of them have their own little nuances.
