This table is from Fowler's Modern English Usage. It succinctly draws the distinctions between such various forms of linguistic manuever as wit and sarcasm. While not always applicable, it is none the less, charming and insightful.
MOTIVE OR AIM | PROVINCE | METHOD OR MEANS | AUDIENCE | |
humor | discovery | human nature | observation | the sympathetic |
wit | throwing light | words and ideas | surprise | theintelligent |
satire | amendment | morals and manners | accentuation | the self satisfied |
sarcasm | inflicting pain | faults and foibles | inversion | victim and bystander |
invective | discredit | misconduct | direct statement | the public |
irony | exclusiveness | statement of facts | mystification | an inner circle |
cynicism | self justification | morals | exposure of nakedness | the respectable |
the sardonic | self relief | adversity | pessimism | self |