"Hypocorism"/"hypocoristic" vs. "diminutive"

I ran across the word hypocoristic for the first time today, in an article on gender in languages and its relationship to sex:

In several of these dialects, nouns denoting girls and unmarried women (irrespective of age), and including hypocoristics, are of neuter gender.

I had never heard this word, so Googled it. Wiktionary and Wikipedia both have articles on the term, but from their definitions and examples, I can't seem to tell if it is a synonym for diminutive, or if it merely overlaps. Other sources don't help either: “Denoting, or of the nature of, a pet name or diminutive form of a name.”

So, I'm wondering if there is a difference between hypocoristic or hypocorism and diminutive (when used to refer to a form of a word or name; obviously dimunitive can also refer to something physical, while hypocorism/hypocoristic appear to exclusively refer to words or names), or if they are just synonyms in that usage.

According to the following sources a hypocorism is a pet name and as such can also be a diminutive, ( when used as a diminutive the two words can be considered synonyms).

Hypocorism (dictionary.reference.com):

• 1. a pet name.

• 2. the practice of using a pet name.

• 3. the use of forms of speech imitative of baby talk, especially by an adult.

• A hypocorism is a nickname that shows affection or closeness (www.vocabulary.com)

  • If your dog's name is Buster but you tend to call him "Sweetiecakes," you're using a hypocorism. A pet name is a hypocorism, and so is the addition of a diminutive suffix to the end of a name, like when you change the name "Bill" to "Billy." Some hypocorisms are as straightforward as changing "Melissa" to "Missy," and others are strange terms of endearment, like your mom calling your dad "Boopsy" when she thinks no one can hear. The Greek root word is hypokorizesthai, literally "to use child talk."

Quotes:

• This must be an offshoot of my brother's enthusiasm for hypocorism . He was always inventing idiotic nicknames for people. -- Adam Davies, Goodbye Lemon , 2006
• Powsoddy, a now obsolete name for a pudding, was also used as a hypocorism in the late sixteenth century, paralleling the affectionate use of the word pudding itself in our own century, though lovers usually alter the pronunciation to puddin. -- Mark Morton, The Lover's Tongue , 2003