No need to worry – I will not be going into the technical side of things, just the cosmetic.
In our application, both chrome and nickel plating provide protection as well as being decorative. However nickel will dull and tarnish with age and handling/use, while chrome will stay bright for decades, as long as it is not scratched.
Which colour should you choose?
It depends on personal preference and what is currently on your guitar. Mixing chrome and nickel in close proximity may be noticeable, although that didn’t stop Leo Fender!
Contrary to what some believe, both chrome and nickel are bright polished finishes. Satin or “dull” nickel plating is available, however it will almost always be described that way. I think the confusion comes from people wanting nickel for the dull appearance and have only seen older tarnished examples, not realising that they were once shiny. Or they’ve only seen Callaham Tele bridges, which are dull/satin nickel plated and they think that is the standard nickel plating!
Without seeing both side by side it is sometimes hard to distinguish between the two. Chrome has a slightly blue tint, while nickel has a slightly yellow, “warmer” hue. The depth of this colour can also vary from manufacturer/plater to another, and also from batches from the same manufacturer.
Finally, while nickel will dull and tarnish with use it can be polished back up to near new condition most of the time.
(The last picture is in natural light, with no adjustments. This highlights how photographs can exaggerate the difference between the two – certainly side by side in person the difference is plain, however in reality the chrome is less blue and the nickel less yellow.)