Nickel Silver and Cupro-Nickel are very similar:
http://pages.zoom.co.uk/leveridge/nickel1.html
Note the following from the above website:
Nickel Silver, German Silver and related alloys
Resources for the metalsmith and collector
What is nickel silver?
Nickel Silver is the generic name for any of a range of non-precious bright silvery-grey metal alloys, composed of copper, nickel and zinc. Despite its name it contains no real silver. It is also commonly called German Silver.
Nickel Silver gets its name because its colour matches that of silver reasonably, and because it was used as a low status substitute for silver in the 19th century (There was then no effective trades desciption legislation to prevent confusion of this alloy with sterling silver).
Nickel Silver was (and still is) widely used for the commercial production of industrial components, housewares, flatware and cutlery, and as the metal substrate for silver-plated goods, hence the term EPNS = Electro-Plated Nickel Silver.
Nickel Silver was formerly widely used in costume jewellery and as the substrate for silver and gold plated jewellery. Due to the high propensity of nickel to induce dermatology problems and allergy, recent legislation in the EU has restricted the use of nickel in jewellery.
There are many different formulations of alloys which fall within the general term of "Nickel Silver". All contain copper, nickel and zinc, while some formulations may additionally include antimony, tin, lead or cadmium. A representative formulation (Alloy No.752) is 65% copper, 18% nickel, 17% zinc.
The US 5 cent coin, known as the "nickel" (introduced in 1866) is minted from an alloy of 75 per cent copper and 25 per cent nickel.
History
The family of Nickel Silver alloys has been known since the early 18th century and were initially developed in the far east. European traders brought back metalware goods which were described using the Indian word Tutenag or the Chinese word Paktong. This new alloy with its properties of strength, relatively easy working and silvery colour began to be used for a range of consumer goods, but it was not until the 1840s that the alloy was developed in its modern formulation. By then firms such as Elkington in England and Berndorf in Austria were looking for a stable, cheap, silverish metal as a substrate for the new process of electroplating. Hence EPNS was born, and its German equivalent Alpacca. Argentum and Electrum were other tradenames for electroplate.
The word nickel is shortened from of the German word Kupfernickel meaning niccolite ore. The word literally means copper demon, and was so called by German miners because it was often confused with genuine and valuable copper bearing ore.
From Websters Revised Unabridged Dictionary (1913)—
German silver (Chem.), a silver-white alloy, hard and tough, but malleable and ductile, and quite permanent in the air. It contains nickel, copper, and zinc in varying proportions, and was originally made from old copper slag at Henneberg. A small amount of iron is sometimes added to make it whiter and harder. It is essentially identical with the Chinese alloy packfong. It was formerly much used for tableware, knife handles, frames, cases, bearings of machinery, etc., but is now largely superseded by other white alloys.
Bibliography: A.Bonnin Tutenag and Paktong, Oxford 1924.
W. D. John, Paktong, Newport, Mon. 1970.
Paktong Keith Pinn 1999, Antique Collectors' Club; ISBN: 1851493247
Current and historical names for some metal alloys not in the Nickel Silver family.
What is Monel?
Monel (or monel metal) is a trademarked name for a range of corrosion-resistant bright metal alloys containing typically 67 percent nickel, 30 percent copper, and trace proportions of iron, manganese, and other elements. It is not a synonym for Nickel Silver and should not be confused with it. Monel is more expensive than Nickel Silver because of the high proportion of nickel and its more specialist applications.
What is Gun Metal
An alloy in the bronze family, used especially where resistance to wear and corrosion is desired. Clasically, an alloy of Cu 88 %, Sn 10%, Zn 2%, traditionally used for making cannon and other industrial products. Also used loosely to describe other dark-grey cast metals such as found in toys, badges, buckles etc.
What is Pinchbeck?
Pinchbeck is a yellow metal alloy in the brass family. Invented by Christopher Pinchbeck in the 18th century, it was claimed to be a secret recipe, but is generally believed to be 83% copper and 17% zinc. This ratio optimises the gold matching colour of the alloy. Commonly known as "poor man's gold", it and similar alloys were widely used in costume jewellery, and as the metal substrate for fire gilding and (from 1840) gilt electroplating. Now included under the generic name "Gilding Metal".
What is Spelter?
Spelter is an alternative name for the metal zinc, especially when used in decorative arts manufacture and casting. Spelter castings were often patinated to imitate more valuable bronze.
What is Tutania?
Tutania is an alloy of copper, antimony, zinc and tin patented in 1770 by William Tutin whose Birmingham firm (Tutin and Haycroft) used it in commercial production of housewares.
What is Cupro-Nickel?
A silvery-coloured binary alloy of copper and nickel. Widely used for minting coinage. It is also called copper-nickel, especially in US usage. In the UK it has been used since 1947 for "silver" coins, usually in an alloy of Cu 75%, Ni 25%. The alloy in the current 20p coin of the UK is Cu 84%, Ni 16%.
What is Bronze?
Any of various alloys of copper with tin and often zinc. Widely used for minting coinage. In the UK bronze coinage (the copper-coloured coins of 1860-1992) the alloy was Cu 95.5%, Sn 3%, Zn 1.5%
What is Nickel Brass?
Any of various brass coloured alloys of copper with zinc and a small component of nickel. Widely used for minting coinage. In the UK's nickel brass coinage (the twelve-sided threepenny piece) the alloy was Cu 79%, Zn 20%, Ni 1%.
What is "Britannia Metal" ?
Britannia metal is another name for pewter in its modern lead-free formulation, usually 91% tin, 7.5% antimony, 1.5% copper.
Gar-Alloy and Eraydo are now-defunct trademark pewter-type alloys with high zinc content.