Lifetime Points is a different type of currency. Lifetime Points are used to buy Traits. Also Lifetime Points are used to unlock boxes. Unlike the other currencies, this currency cannot be transfered from SimCash.
You can earn Lifetime Points by:
Read More: Traits and Personality
Traits are used to buy to improve your Sim life. The traits have five levels each. It improves everytime you buy an upgrade. Some traits are more expensive then the other because, some have more benefits, for example, 'Ninja'.
Also with Traits, you can buy trait slots that give your Sim, more traits to add. Once you have started the Sims Social, you one trait slot, to buy a trait. You can gain two 5 more boxes from 3 ,7, 12, 20, and 40. All the trait slots have a cost rate as you advance your Sim level.