Lens confusion

Hope someone can help me out on this one. I'm looking at buying a macro lens and in particular been looking at the Fantasea range. Here is where I get confused: what is the difference between a SharpEye lens and the UCL range?

Here are the specs on each:

UCL-05LF +6 Macro Lens

•Description: +6 diopter close-up lens

•Bezel Material: Hard anodized aluminum with black hard coating

•Lens Construction: 3 groups and 4 elements

•Lens Coating: AR multi layer coating

•Threads: 67mm (front and rear)

•Dimensions: 74 x 41.1 mm / 2.9 x 1.6 inch

•Weight: 254 g / 9 oz

SharpEye M67 +8

•Lens Construction: 2 groups, 2 elements

•Focal Length/Diopter: 125mm / +8 (Underwater)

•Features a 67mm thread mount

•Lens Coating: multi AR coating + water repellent coating (outer surface)

•Barrel Material: Aluminum with black anodize

•Weight: 135g

•Dimensions: Ø 72mm x 22.5mm (D)

All I can make out is the UCL is longer and heavier, but what get me is the construction specs. What does 2 groups, 2 elements vs. 3 groups, 4 elements mean to me as the user? Is the latter a better makeup of the lens though the SharpEye has higher magnification properties?

Any clarification will be appreciated.

Elements refers to the number of glass elements or actual lenses (100% glass) making up the complex lens (multiple lenses, metal, etc.). Since lens elements are frequently glued together, a group of elements glued together is referred to as a group. For example a simple achromat lens can consist of two elements in one group - a number of long focus lenses made in the past were of this design such as the 400 and 560mm f/6.8 Telyts made by Leitz (company making Leicas before the name was changed).