Most manufacturers of sockets produce two varieties: impact, and chrome. As far as a I know the only difference is impact can be used in impact wrenches. Why would you ever get a socket set that isn't useful for impact wrenches? The price difference seems absolutely minimal.
Are chrome sockets better at anything?
Yes. The normal sockets have thinner walls, and thus are able to reach bolts that are set close-in. (The designers of those machines need to be close, and are well aware of the dimensions of standard sockets; though there is an argument to be made that socket head cap screws are the better choice for close clearances).
Also, every socket has a bevel to help it center on the nut, and that bevel has a height. This precludes it from being used with extremely shallow nuts, such as those found on sandwich mounts, glands, conduit nuts, etc. Impact sockets have a deeper bevel, which makes it harder to work with thin nuts or bolt heads.
Impact sockets are much thicker and robust than, what you call, "chrome sockets", which are much thinner and engineered to withstand human strength, not impact drivers.
With a high torque impact driver, you could easily crack open a non-impact socket and maybe send pieces flying...wear protective goggles if you try using "chrome" sockets on an impact driver. ....Actually it's a good idea to wear protective goggles in either case, but esp. for sockets not approved for use on an impact driver.
More often, chrome sockets are bi-hex, although impact are available as such. Single hex impact are usually better, but the wall thickness is greater, making them not-so-useful in tight situations.
