What is the difference between the random password types?

Alphabetic generates a random password made up of only letters. 
Example: qpnhbejdqj

Alphanumeric generates a random password made up of letters and numbers.
Example: 9n735txvof

Word generates a random password by putting together 3 words in random order. 
Example: funnymeowwars 

Wordnumeric does the same thing as Word but adds 3 random numbers to the end.
Example: funnymeowwars634

Gibberish makes a random password out of letters, numbers, and keyboard symbols. This is the most secure type. 
Example: !sfp+c:/[,