In Spanish the letters b and v should be pronounced the same. However, native Spanish speakers may pronounce them differently by choice.

b
Trabajo en el tabaco.
     I work with tobacco.
Prohibido beber.
     Alcohol prohibited.
Mi papá tiene bigote.
     My dad has a mustache.
flor bonita.
     pretty flower.
Yo estoy aburrido.
     I am bored.

v
El lavabo está sucio.
     The sink is dirty.
El césped es verde.
     The grass is green.
La primavera es maravillosa.
     Spring is wonderful.
libro nuevo
     new book
los vuelos
     the flights