Originally Posted by performula
Vernier = dial?
Vernier are the "old style" calipers with one side of the scale fixed to the frame/upper jaw and the other side of the scale moving with the lower jaw. You then had to read the vernier(s) in order and "interpolate" the last decimal point (typically 1/10,000). Dial calipers have an analog dial that reads the thousandths after the inches and tenths are read from the vernier scale. You can then (if needed...) approximate the ten-thousandths to + or - 5/10000 pretty easily.
My Harbor Freight digital caliper (few years old now) gives direct readout to, essentially, 1/2 of one thousandth (the ten thousandths frame only reads the 5's and 0's) as does the nice new $8 "composite" digital caliper I bought there this week. (**NOTE** I'd hold off on these composite units until someone can double check that they actually READ OUT to .001". Meantime, the stainless pair are a whoppin' $16 which is a SCREAMIN' deal.)
The fact that you don't know what the differences in calipers are tells me that any of these are 1000% accurate enough for your use. If you had need for more accuracy than that you're doing pretty fine machine work and would know the tools. The only thing approaching that level of accuracy in RC would be machining engine parts and the guys doing that are probably using micrometers, dial indicators. and very accurate measurement fixtures.
Quit psyching yourself out and buy the Harbor Freight unit.