Teacup is a term used by both breeders and buyers to describe dogs that are very tiny "can fit in a teacup" is how that started. Not a term used by good breeders.
Miniature is used as a breed description--like Miniature Poodles, Min pins, schnauzers and the like. The size or weight of these dogs is determined by the breed standard of each--they are not all the same size just because the word "miniature" is used.
***Edited By: PixiedustPapillons on 12/1/2005 8:16:01 AM*** Reason: sp
If a teacup dog is actually one that size (sometimes they will lie and say it will be that size to get you to spend $) it will usually have many health problems like hypoglicemia (sp?) and it will greatly affect the dogs quality of life. Breeding a teacup dog on purpose is in my opinion inhumane, because the dog will usually suffer. If you want a small dog try a toy size, like a toy poodle or chi.