The Moon is your emotional aspect and somewhat your core. It's supposed to also influence your relationship with your mother and, if you're a man, what type of women you'll marry.
The Sun is your identity is your ego and how you express your identity. So a sensitive/emotional moon (Pisces Moon) might express that that through brashness/action (Aries Sun) instead of feelings. The marriage thing applies to women.
Mercury is how you communicate and use words.
Jupiter is your sense of morality and how you deal with other people but is a bit slow moving the signs change like every couple of years.
The rest of the planets are slow moving so less unique.