+ Clean, crisp, simple aesthetics. Can’t get much more “classic” diver than this. Yet without being a shamefully blatant Rolex homage or Seiko homage. It has its own vibe. I like the 106’s case shape as more
traditional than the more curvaceous 102. I also like that the 106 has
crown guards.

+ Great hands on the 106. Nice shape, with beveled, polished steel; much
more interesting than the plain white 102 hands. The 102’s hands always
bugged me just a little bit, in that the thinner minute hand looked
mismatched to the wider hour hand. And I also like the red &
polished combo of the 106’s second hand better than the red/white/black
on the 102.

+ Much cleaner bezel on the 106, with a simpler bezel insert and less bold outer crenellations.

+ Excellent, attractive dial. Again -- cleaner. Traditional, applied
round dial markers. I like that the 106 has the hashmarks on the chapter
ring versus printed on the dial, and leaves off the 102’s unnecessary 1/5
second hashmarks. The 106 dial is pure black and has a satin sheen – not
glossy, not matte, but in between, with a very subtle sunburst effect.
The 102’s dial is more of a matte dark gray than black. The 106 has less
writing on the dial than the 102. Looks like a higher dial-to-case
ratio than the 102, due to the slimmer bezel.

+ Still has the Marlin on the dial. I dig that.

+ Lume. The 102’s is not fantastic, but is merely okay. However, that’s
mitigated by it having that awesome LED lighting. The 106 has very good,
effective Seiko-style lume. Well done, Casio.

+ The 106 has brushed, beveled lugs, and polished sides. With a less
ornate case, less prominent bezel crenellations, and without the 102’s
double crowns, the 106 projects much less of a blingy overall appearance
than the 102. More understated.

+ The craftsmanship of the 106 seems to be at a whole higher level than
the 102. The attention to detail on the 102 is impressive “for its
price”, but the quality just seems a noticeable notch better on the 106.
I’m referring to the visible quality of the machining, polishing, &
brushing of the case, the precision of the dial detailing, the assembly
quality -- are all just excellent, and without having to add the words
“for the price”. It seems on a par with and compares favorably to any
mid-range Seikodiver, and does not embarrass itself next to my Omega Seamaster Pro.

+ Lug width. The 102 has an awkward 21mm lug spacing. The 106 is 22mm,
which gives the owner much broader strap choices. The watch is perfectly
proportioned with its lugs and strap.

+ Crystal. The 102 is domed, but its thickness and shape actually makes
it look a little milky when viewing at an angle. The 106 is a flat
crystal, is perfectly clear, and the top surface projects very slightly –
it stands less than 1mm proud above the bezel. It’s gorgeous. Both are mineral glass.

+ Strap. The 106 strap is soft, velvety, matte resin similar to a Seiko diver strap. The 102 is harder, more plasticky, less flexible. Many have
complained about the 102's strap being uncomfortable, although I think
it's fine. But the 106's is better. Although I do like the curved end to
the 106's strap that fits the contour of the case and leaves no gap.

+ The 106 is available in both bracelet and resin strap versions. 102 only comes on a resin strap. I can't comment on the quality of the steel bracelet .

+ A silver dialed variant, and blue bezel insert variant, are available
on the 106 (although I greatly prefer the black dial, black bezel “base”
model).

+ Notice the small words on the bottom of the 106’s dial: “JAPAN MOV’T”.
The second hand hits the markers very well on my example. The caseback is stamped “Cased in China”. Versus the 102 being all-made-in-China (not that it matters very much).