They indicate place and quantity respectively. But not only that! These particles are particular and indicate 'complements'. The particle 'NE' indicates a number of things but is also used with pronominal verbs to change the meaning of the verb. The particle 'CI', on the other hand, has many uses because it can indicate a place or it can be a complement pronoun, or it can be part of a reflexive verb. For example, I can say, 'noi CI SVEGLIAMO sempre alle 9.00 a.m.'