An analog meter has a set of rotating platters which are visible through the glass case. Also, smart meters usually have IR input windows on the front of the casing.

One of the biggest problems with these smart meters are sampling errors. Because they sample in digital increments a noisy line can throw off the meter and really hike your bill. Be aware of this if you have above-ground power lines and call your electric company if you notice any branches getting near the lines. The brushing of tree-branches against the lines can generate enough noise to cause sampling errors.