It varies on many different levels, each individual will have their own unique responses. The most average of terms defining these types of kisses, for this day and age, are as follows:
Kiss on forehead?
- "I adore you and respect you"
Kiss on cheek?
- 1) "It was nice to see you again" or 2) "Your cute and I'll see you later" or 3) "Goodbye"
Kiss on lips?
- a simple sign of affection between two people. Either as "mother / daughter" or "bf / gf"
Kiss on neck?
- "I find your attractive and am comfortable with you"
Kiss on collarbone?
- "I am arroused from you and would like to do something"
Kiss on ear?
- Very uncommon, I'm not sure to the meaning behind this one.
Kiss on chest (not on breast but right above)?
- for sexual or emotional arrousal while identifying the person's comfort level.
Rough kiss? ("Making out")
- To build sexual tension to lead towards sexual actions.
- Sign of affection similar to the "kiss on the lips" above; however, more passionate and usually only shared between a "bf / gf" relationship which includes but isn't limited to "husband / wife". Usually withholding a lot of strong feelings for the opposite person.
- Sign of sexual arrousal signifying a desire to fool around sexually.
Thank you, nice question!