The answer to this and many other questions is found in the FAQ at Caudata Culture:
http://www.caudata.org/cc/faq/faq.shtml
"What is the difference between a newt and a salamander?
Surprisingly, there is no really meaningful difference. The distinction is more historic than scientific. Newts are a subgroup of salamanders. All newts are salamanders, but not all salamanders are newts. The following are the things that distinguish newts from salamanders.
A salamander is called a "newt" if it belongs to one of the following genera: Cynops, Echinotriton, Euproctus, Neurergus, Notophthalmus, Pachytriton, Paramesotriton, Pleurodeles, Taricha, Triturus, or Tylototriton.
Newts generally spend more of their adult lives in the water than salamanders. However, there are exceptions (terrestrial newts and aquatic salamanders).
Newts generally have more distinctive differences between the sexes and a more complex aquatic courtship. Again, there are exceptions."
