What is difference between buspar (buspirone) and celexa as far as which brain chemicals they work on?

Serotonin. Escitalopram (Celexa) is a serotonin-specific reuptake inhibitor, said to be ultra selective. Buspirone (Buspar) works on the serotonin system as a 5HT1A agonist. Although I admire inquiring minds, I can't imagine how this information is helpful to you. It is helpful to me. I hope you can find a way to use it.