The Collaborative International Dictionary of English v.0.48:

Kail \Kail\, n.
   1. (Bot.) A kind of headless cabbage. Same as Kale, 1.
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   2. Any cabbage, greens, or vegetables. [OE. or Scot.]
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   3. A broth made with kail or other vegetables; hence, any
      broth; also, a dinner. [Scot.]
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   Kail yard, a kitchen garden. [Scot.]
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The Collaborative International Dictionary of English v.0.48:

Kale \Kale\, n. [Scot. kale, kail, cale, colewort, Gael. cael;
   akin to Ir. cal, W. cawl, Armor. kaol. See Cole.]
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   1. (Bot.) A variety of cabbage in which the leaves do not
      form a head, being nearly the original or wild form of the
      species. [Written also kail, and cale.]
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   2. See Kail, 2.
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   Sea kale (Bot.), a European cruciferous herb (Crambe
      maritima), often used as a pot herb; sea cabbage.
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WordNet (r) 3.0 (2006):

kail
    n 1: a hardy cabbage with coarse curly leaves that do not form a
         head [syn: kale, kail, cole, borecole, colewort,
         Brassica oleracea acephala]
    2: coarse curly-leafed cabbage [syn: kale, kail, cole]